CA1267899A - Compounds for site-enhanced delivery of radionuclides and uses thereof - Google Patents

Abstract

Abstract of the Disclosure A dihydropyridine ? pyridinium salt type of redox, or chemical, delivery system for the site specific and/or site-enhanced delivery of a radionuclide to the brain is provided. A chelating agent capable of chelating with a radionuclide and having a reactive hydroxyl. carboxyl, amino, amide or imide group is coupled to a carrier moiety comprising a dihydro-pyridine ? pyridinium salt nucleus and then complexed with a radionuclide to provide a new radiopharmaceutical that, in its lipoidal dihydropyridine form, penetrates the blood-brain barrier ("BBB") and allows increased levels of radionuclide concentration in the brain, particularly since oxidation of the dihydropyridine carrier moiety in vivo to the ionic pyridinium salt retards elimination from the brain while elimination from the general circulation is accelerated.
This radionuclide delivery system is well suited for use in scintigraphy and similar radiographic tech-niques.

Description

g COMPOUNDS FOR SITE-ENHANCED DELIYERY OF
RADIONUCLIDES AND USES THEREOF

Field of the Invention The present invention relates to a dihydro-pyrid1ne = pyridinium salt type of redox, or chemical, delivery system for the si~e-speci~ic and/ar site-enhanced delivery of a radionuclide ~o the brain and other organs. More particularly, this invention relates to the discovery that a che1ating agent capable IO of chelating with a rad~onuclide and having a reactive hydroxyl, carboxYl. amino, amide or imide group can be coupled to a c rrier moiety comprisin~ a dihydropyridine ~--- `pyridinium salt nucleus and then complexed with a radionucl1de to provide a new radiopharmaceutical 1~ ~hat, ~n ~ts lipoidal dihydropyridine form, penetrates the blood-bra~n barrier ("e~8") and allows ~ncreased levels of radtonucl1de concentration 1n the brain, particularly since oxidation of the dihydropyridine carrier moiety ~n vivo to the ionic pyridinium salt retards elimination from the brain while eli~ination from the general c1rculation is accelerated.
The presert rdd~onucl~de delivery system 1s well suited ~or use ln sc~nt~graphy and similar radiographlc techn1ques.

:

,~ .

8~g Back~round of the Invent10n Rad~ograph1c technlques such as ~clntigraphy, and the 11ke, f~nd appl1cat10n in biological and med1cal procedures for d1agnosis as well as research.
5 Sc1nt1graphy ~nvolves the use of radiopharmaceuticals;
1.e., compounds contain1ng (or labeled with) a rad~o-~sotope (~.e. radionuclide~ wh-ch upon introduction 1n~o a mammal become localized in specific organs~
t1ssue, or skeletal materlal that are ssuqht to be 10 imaged. When the radiopharmaceutical is so local1zed, traces, plates, or sc1nt~photos of the existing diso tr1bution of the radionucl~de may be made by various radiat10n detectors known ~n the art. The observed d1str1but10n of the local1zed radionuclide can then be used to detect the presence of patholog1cal con-d1t10ns, abnormali~1es, and ~he like. Radiopharmaceuticals are thus often re~erred to as radiodiagnostics.
In many cases, rad~opharmaceuticals are prepared us~ng target-specific chelat1ng agents which provide ~ br1dge connect1ng a rad10nucl1de, such as a radlo-active metal like technetium-99m, or the like~ and a mater1al wh1ch w111 temporarily local1ze in the organ, t1ssue, or skeletal mater1al wh1ch 1s to be imaged. Typ1cal chelat~ng agents for such purposes ~re: polyd~entate l~gands that ~orm a 1:1 ~or 2:1 119~nd:radio,1ctive metal complex macrocyclic ligands ~2~i~8~3 - . of appropr~te ring s~ze ~nd preferably where all coord~nating a~oms are ~n a planar configuration;
and bicycl~c or polycycl~c 1~gands ~hat can encap sulate the ~ad~oactiYe metal.
It ~s a well established fact that the delivery of drugs, includlng rad~opharmaceuticals~ to the bra~n ~s often ser~ous!y lim~ed by ~ransport and ~etabol ~sm factors ~nd, more specifical ly, by the func~1Onal barrier of the endothelia~ brain;capillary wall deemed the blood-braln barrier. Site-specif~c del1Yery andjor susta1ned delivery of drugs to the bra~n are even more difficult.
It has been previously suggested to deliver a drug spec1es, spec~fically N-methylpyritinium-lS 2~carbaldox~me chlor1de (2-PAM), into the brain, the actiYe nucleus o~ wh~ch ~n and of jtself con-st'tutes a quaternary pyridinl~m salt~ by way of the dihyd:ropyr~d~ne latent~ated prodrug form ~hereof.
Such approach Is consp1cuously delimited to relatively smal1 molecule quaternary pyridinium ring-containing drug spec1es and does not proYtde ~he overall ldeal result o~ braln-specif~c, sustained release of the des1red drug, with concom~tant rapid elimination Prom the general circulation, enhanced drug efficacy and decreased toxicity. Hence, no "trappingl' in the braln of the 2-PAM formed In situ results, and obvlously no~brain-spec1f1c9 sustained del~very occurs as any consequence there~f: the 2-PAM is eliminated as fsst from the bra1n ~s tt 1s from the general 3~ c~rcutat~on and other organs. Compare U 5. Patents :

Hos. 3,929,813 ~nd 3~962a447; Bodor et al, J. Pharm S ., 67, Ho. 5, pp~ 68~-687 (1978); Bodor et ~1, Sc~ence~ Yol. 190 (1975), pp. 155-156; Shek, H~guch~
and ~dor, ?. Med. Chem., Vol. 19 (1976), pp. 113-117. A more recent extenslon of this approach is descr~be~ by Brewster, D~ssertation Abs~racts Inter-nat~onal, Yol. 43, No. 0~, March 1983, p. 2910B.
It has also been speculated to deliver, e.g., an antitumor agent,~nto the bra~n by utilizing a dihydro-pyr~dine/pyrid~nium redox carr~er ms~ety thereforg but this par~icular hypothes1s necessarily entails der~vatiz~ng the dihydropyridine/pyridinium carrier with a substituent itself critically designed to control the release rate of the active drug species from the quaternary der~vat~ve thereof, as we11 as being crit~cally funct~onally coordinated with the part~cular chemlcal and therapeutlc activ~ty/nature of the ant1tumor drug spec~es ~tself; Bodor et al, J. Pharm. Sci., supra. See also Bodor, "Novel Ap-~ proaches for the Des~gn o~ Membrane Tr~nsport Properties of DruasU, ~n Des~gn of B10phar~aceutical P~pert~es Throu~h Prodruys and Analogs~ Roche, E.B. ~ed.), APhA Academy o~ Pharmaceut~sal Sciences, Washington, D.C., pp. 98-135 (lg76).
More recently, Bodor et al, Science, Vo. 214, December 18, 1981, pp. 1370-1372, have reported on s~te-spec~f~c susta~ned release of drugs to the brain~
The S&lence publ1catlon outl~nes a scheme for specif~c and susta1ned deliYery of drug species to the brain, as dep1cted ~n the follow1ng Scheme 1:

~789g ID~ ~ lOC~ cCoHUMLlcNAl ~ REDucTlo ~) DELIVERY ~ K7 ~ T0 B0DY \
4~'' \ / ELIMINATI0H
tD-DHC1 ID-DHC1 IN THE GRAIH IN CIRCULATORY SYSTEM
AND ORGANS
: ~1 IN YIYO XI IN VIVO
OXIDATION ~ OXIDATION

ID~9C3+ - ENZYMATIC ENZYMATIC - [D-0CI+
IN THE ~RAIH CLEAVAGE CLEAVAGE I IN CIRCULATORY SYSTEH

;14 14 1 1 ELIHI~ATIOH
SCHEME 1: BBB, 8LOOD-LRAIH LAR_IER

Accordtng to ~he scheme ~n Science, a drug [D~ ~s coupled ~o a quaternary carr~er tQC]+ and the rC-QC~
wh1ch resul~s 1s ~hen reduced chemically to the lipo~dal d1hydro form ~D DHC~. After administration of ~D-DHC~
~n vivo, ~t Is rapi:tly d~stributed throughout the body~ Including the braJn. ~he dihydro form tD-DHC~
is then in situ oxid~zed (rate const~nt, k1) (by the NAD = NAD~ system) to the ~dea~ly inact~ve orig~nal ~D-QCJ~ quaternary salt whlch. because of its ionic, hydrophf1~c character, should be rapidly eliminated from the general c~rculat~on of the body, while the blood-braln barrier should prevent its elimination from the brain (k3 ~ k2; k3 ~> k7)- En y cleavage of the tD-QcJ+ that is "locked" in the brain effects a sustained delivery of the drug species [D], followed by lts normal elimination (k5), metabolism.
A properly selected carr~er ~QC]~ will also be rapidly el~minated from the braiR ~k6 ~' k2)- Because of the facile el~mination o~ ~D-QC~ from the general cfrculat~sn, only minor amounts of drug are released 1n the body (k3 ~ k4); ~D~ will be released primari7y ~n th~ brain (k4 ~ k2), The overall result ideally will be ~ bra~n-spec1f1c susta~ned release of the target drug specfes.
Bodor et ~l have reported, in Science, their work with phenyle~hy~a~fne as the drug model, which was coupled to n~cot~nic ac~d" then quaternized to glYe compounds of ~he ~ormula ,~ CoNHcH2cH2~
~ O J ~ (R=CH3 or CH2 ~ ) .~6~

whfch were subsequently reduced by sodium d~th~onite to the corresponding compounds of the formula ,~ CONHCH2CH2~
R CH2 or CH2 ~ ~.
R

Testing of the ~-methyl der~vative in vlvo supported the cr1teria set forth in Scheme 1. Bodor et al speculated that various ~ypes of drugs might possibly be del1vered using the depicted or analogous carr~er sys~ems and ~ndicated that use of ~-methy7n k otinic ~c~d esters and amides and their pyridine ring-sub-- 10 st~tuted der~vatives was being studied for delivery of amino- or hydroxyl-containing drugs, includ~ng s~al1 peptides, to the brain. No other possible specific carriers were t1sclosed.
Other reports of 80dor et al's work have ap-peared ln The Friday Even~ng Post, Aug~st 14~ 1981~
Health Center Commun~cat~ons~ University of Florida, Ga1nesville~ F10r~da; Chem~cal ~ Engineerlng~ News, December 21, 1~81, pp. 24-25; and Science News, Janu~ry

2, 1982, Yol. 121, No. 1, page 7. These publications do not suggest any carr~er systems other than the specif~c N-methyl and N-benzyl nicotinic acid-type carr~ers disclosed ~n the Sc1ence publicat~on. O~her c7asses of drugs as well ~s a few spec~ic drwgs~
~re ment10ned ~s possib7e candidates for derivat~-zation; for example, steroid hormones, cancer drugsand memory enhancers are ~ndicated as targets for poss~ble future work, as are enkephalins, and ~2~

speclf1ca11y, dopam~ne and ~estosterone. The pub-ll~atlons do not suggest how to link such drugs to the carr~er, except posslbly when the drugs are s~mple str~tures contain~ng ~ slngle NH2 or, perhaps, s1mple str~ctures conta1n~ng ~ sfngle OH, of the pr~mary or secondary type, ~s ~s the case with phenylethylamine or testosterone. There ~s~ for examp1e, no suggest~on of how one of ord~nary sk~ n the art would form a drug-carr~er comblnat~on when the drug has a more compl1cated chem~cal structure than phenylethylamine, e.g.~ dopamine or an enkephalin. For further details concern~ng the work w~th phenylethylamine, dopamine and ~estosterone, see also Bodor et al, J. Med. Chem., Vol. 26, March 1983~ pp. 313-317; Bo~or et al, J.
Med. Chem., Yol. 26, Apr~l 1983, pp. 528-534; Bodor et al ~ Pharmacolo~y and Therapeutics, Vol. 19, NoO
~. pp. 337-386 (Apr~l 1983), and Bodor et ~l, Sc~erce, Vol. 221, July 1983, ppO 65-67.
In view of the fore~olng, lt 1s apparent that there has existed an acutely serious, long-standing need for a truly effective, generic but nonetheless flexible, method for the site-specific or sustained deliveryt or both, of drug species to the brain.
This need has been addressed in International Patent Application No. PCT/US83/00725 (fi1ed by UNIVERSITY
OF FLORIDA on May 12, 1983 and published under International Pub1ication No. W083/03968 on November 24, 1983), which provides such a generic method for site-specific, sustained delivery of drugs to the brain utilizing a dihydropyridine=pyrid;nium salt type of redox carrier system. Accordin~ to the PCT
application, a drug (typically having a reactive 1~7~9 -OH, -COO~ or -NH2 group) can be coupled to a dihydropyridine ~ ~ pyridinium carrier; the lipoidal dihydro form of the drug-carrier system readily crosses -the blood-brain barrier; the dihydrapyridine moiety is then oxidized in vivo to the ideally inactive quaternary form, which is "locked in" the brain, while it is facilely eliminated from the general circulation; enzymatic cleavage of the "locked in" quaternary effects a sustained delivery of the drug itself to the brain, to achieve the desired biological effect. Diagnostic agents such as radiopharmaceuticals are generally disclosed in International Publication No. W083/03968 as possible candidates for the carrier system, but the synthetic approach of tha-t publication, which utilizes the drug itsel~ as the starting material, is not desirable when radioactive materials, especially relatively short-lived radionuclides, are involved. Moreover, in -the case of radionuclides, the earlier objective of an ideally inactive form locked in the brain would not achieve the desired result. Thus, a serious need still exists for an effective general method for the site-specific and/or sustained delivery of a desired radionuclide to the brain.

Summary of Invention It has now been found that a chemical delivery system based upon a dihydropyridine ~ pyridinium salt type redox carrier is uniquely well suited for an effective si-te-specific and/or sustained andjor enhanced delivery of a radionuclide to the brain or like organ, via novel carrier-containing radio-pharmaceuticals, and novel 78~9 carr1er-conta~n~ng chelat~ng agents and novel carrier-conta~n~ng precursors thereto~ useful ~n the preparat~on of said rad1Opharmaceuticals. In one aspect, the present 1nvention thus proYldes novel carr1er-canta~ning chelating agent precusors hav~ng the formula ~ [QC~y mx-n (I) where1n ~ ~s the res~due of a ehelating agent capable of chelat~ng wlth a ~etall~c radionuclide, said chelat~ng agent having at least one reactive fun~-t~onal oroup selected from the group consisting of amino,carboxyl, hydroxyl, amide and t.mide. said functional group being not essentlal for the complexing properties of said chelat~ng agent, said residue being character-~zed by the absence of a hydrogen atom from at least one of said reactive funct~onal groups o~ the chelat$ng agent; y ~s l or 2; ~QC+J jS the hydrophilic, ionic pyr1d~n~um salt form of a dihydropyridine~__ pyri d~n1um salt redox carrier; X~ ~s the anion of a pharmaceutlcally acceptable organic or ~norganic acid;
n ~s the ~alence of the ac~d anlon; and m is a numbe~
which when mult~pl~ed by n ~s equal to y~
In another aspect, the present ~nvention provides novel carr~er-contain~ng chelating agents having the formula ~ DHC~y (II) and the non-toxic ~ armaceut~cally acceptable salts U and y are defined as above, and 3L~6~ i9 ~DHC3 ls the reduced, b100x1d~zable9 blood-brain barrler peneSrat1ng form of dlhydropyr1d1ne = pyr~-dtnium sal~ redox carr1er.
In yet another aspect, the present 1nvent~on prov1des, as an effecttve radionuclide delivery system, novel carrler-conta1n1ng radlopharmaceuttcals of the formula r~
DHC]y (III) ~nd the nor-toxtc pharmaceut~cally acceptable salts IO thereof, where1n M ~s a meta11ic radionuclide and the rema~ntng structural variab7es are defined as before;
~n other words, (III) is the chelated, or complexed, counterpart of (II), formed by complexing the novel carr~er-contatn1ng chelat1ng aqent of formula (II) wlth a rad10acttve metal. When a radiopharmaceutical of for~ula (III) 1s admin1stered, it readily pene-trates the B~B. Ox1datfcn of (III) in v1vo affords the correspond~ng pyr~d1n1um salt of the formula ~ QC~y mX~n tlV) ~here~n ~he structural var1ables are as defined above.
Because of Its hydrophilto, ion~c na~ure~ the formula (IY) substance 1s ~locked-tn" the brain~ thus allowing rad109raph~c 1mag~ng of the radionuclide present 1n the complex (IV). Wh11e the quaternary Nlocked-1n"
for~ w~17 ~radually cleave to release the carrier mo1ety and the chelate portton of the molecule, such cleavage will generally occur~af~er the most deslrable 789~3 perlod for rad~ographlc Imaging has already passed.
It ls generally considered ~ost des~rab1e, from the - standpoin~ of patient and technician safety~ to 10a~e the target area as soon as posslble after ad-~nlstratlon and to use relatively short-11ved radio-~sotopes. Un~er such c1rcumstances, the ~locked-in"
quaternary furm w~ kely not degrade to the non-carrler-containlng chela~e until after the radlo-actlYlty has decayed to a cons1derable extent. Thus, 1~ the present lnventlvn does not ln fact prov~de a : system for delivery and l~ag~ng of previously known radlopharmaceuticals; by the time the present delivery system deyrades to a chelate of a known chelatfn~
a~ent and a radioactive metal, sald chelate will genera,lly no longer be suff~clently radioactive for practical imaglng. Moreover, once such degradation occurs, the known chelate 0ay not be retained ln the br~in 1n suff~c1ent a~ounts to allow Imagin~ thereof.
Thus, in contrast to the teachings of the Bodor et al publications and the aforementioned PCT application, which emphasize the desirability of an inactive quaternary form locked in the brain, the present invention pro-vides, and indeed requires, an active quaternary form locked in the brain in order to allow effective radionuclide imaging.
The present chelate/carrier system for radio-nuc?ldes ls har~cter~zed by enhanced efflcacy and decre~sed tox~city. Indeed, consistent herewith system~c tox~c~ty is signlficantly reduced by ac-celeratlng the el~mlnation of the quaternary carrier ~ystem from,the general clrc~lat~on.
Technetlum-99m ls a pre~erred radlonuclide for diagnost~c purposes because of its favorable rad;-~L2~;7~39 atlon energ~, Its relatlve1y short half-life, and the absence of corpusoular rad~atlon~ and ~s preferred for use ~n the present fnvent~on. Other radionucl~des that can be used diagnost~cally here1n in a chelated form are cobalt-57, gall~um-67, gall~um 68, 1nd1um-111, ~ndlum-l1lm, and the llke.

Detailed Descr~ptlon of ~he InYentlon The followlng def~n~t~ons are applicable:
. The term ~drug~ as used herein means any sub-stance 1ntended for use 1n the diagnosis. cureD m~ti gat~on, treatment or preventlon of disease in man or other anSmal.
The term Ul~poSdalu as used herein designates a carr~er molety wh~ch 1s llp~d-soluble or lipophilic.
lS The express10n ~non-tox~c pharmaceutically accep table sal~sW as used hereln generally 1ncludes the non-tox1c salts of products of the invention of structures (II~ and (III3 here1nabove ~ormed w~th non-tox1c~ pharmaceut~cally acceptab7e inorgan1c or organlc ac1ds of the general formula HX. For example, the salts 1n.clude ~hose der~ved from inorganic acids such as hydrochlorlc, hydrobromic, sulfuric, sulfam1c~
phosphor1c, nltrlc and the 11ke; and the salts pre-pared from orqan1c ac1ds such as acetic, propionic, succ~n1c, glyco~ic, stear~c, lactic, mal~c, tartaric, c1trlc, ascorb~, pa~olc, malelc9 hydroxymaleic, phenyl-acet~c, glutam1c~ benzoio, sa71cylic, sulfan~lis3 fumar~c~ methanesulfonfc, toluenesulfonic and the like.
The express~on ~anlon of ~ pharmaceutically ~cceptable organ1c or 1norgan1c ~cSd" as us~ed hereSn~ e.g. 1n connect~on w~th structures ~I) and (IV3 above, is in-tended to gnclude an10ns of such HX acids.

~2~789~

It will be appreciated from the foresoing that a compound of formula (III) may be administered as the free base or in the form of a non-toxic pharma-ceut~cally acceptable salt th~reof, i.e. a salt wh~ch S can be represented by ~he formula (~3 IDHC~y 'HX

wherein M, ~ , [DHC], y and HX are defined as before;
and that, regardless of the actual form in which the compnund is administered, it will be converted ;n 10 vivo to a qua~ernary salt of formula ~IY), the anion X being present in viYo. It is not necessary that the anîon be:introduced as part of the compound ad-ministered. Indeed, even when the compound of formula ~III) is used in its salt form, the anion of t~.e formula (IY) compound in vivo is not necessarily the s~me as ~ha~ present in the formula (III) compound. In fact, the~ exact identity of the anionic portion of the compound of for;mula (IY) is immaterial to the:
in vivo transformation of (III) to (IV).
In the expression "at least one reacti~e functional group selected form the group consisting of amine, carboxyl, hydroxyl, amide and imide" as ~sed here~n, the designated reactive functional groups have the following meanings:
The word "amino" means any primary or secondary am~no funct~on, i.e. -N~2 or -NHR where R is typically C1-C7 alky;l or is a~portion of the chelating agent residue itself.~ rhe~secondary amino function is also represented herein as -NH-, particularly:since the : exact identity of the R:portion of -NHR îs immateri-al, just so long as it does not prevent the formation of the chelating agent residue and its linkage to :

~2~ g the carrier moiety or otherwise interfere with the objects ~f this in~ention.
The word "carboxyl" means a -COOH function.
The word "hydroxyl" means an -OH function.
The word "amide" means a carbamoyl (-CONH2) or substiSuted carbamoyl (-CONHR9 where R is typically Cl-C7 a7kyl) functional group. The -CONHR group ~ay also be represented herein as -CONH-, since the exact identity of the R portion of -CONHR is immaterial, just so long as it does not prevent the formation of the chelating agent residue and its linkage to the carrier moiety or otherwise interfere with the objects of this invention.
The word "i~ide" means a functional group having the structure -C ~
/ NH
-C
~0 ~hat is, the structure which characterizes imides (i.e. compounds such as succinimide, pathalimide and so forth).
The expression "said functional group being not essential for the comPlexing properties of said chelating agent" is believed to be self~explanatory. Any func~ional group in the chelating agent which can be linked to ~he carr1er mo1ety wl~hout destroying the chelating agent's ability to complex with the radionuclide is considered herein to be not essentia~l for complexing properties. On the other hand, derivation of a functional grOup which would lead to a carrier-containi~g structure wh1ch would be incapable of complexing with a radionuclîde is not within the ambit of this invention.

~713~9 In accord with the present ~nventlon,:the sus-talned'del1very of a radlonucllde to the bra1n 1n sufflc~ent concentratlons for radlolmaglng can be.
effected wlth much lower ooncentrations ~n:the peripheral clrculat~on ~d other tissues. The present ~nvent~on of course w~l~ allow such imaging of any other organs or ~lands In wh~ch suffic~ent radio-actlv~ty accumulates. Thus, for example, ~t 1s expect-ed thdt the quaternary form (IY) wh7ch is locked ~n the braln will be locked ~n the testes as well. See the afor~ entioned PCT applic~70~ `~ hl,c~
~/' The nove~ radionucllde de~very system of th~s invention beglns wlth the preparation of the novel carrfer-contalnlng che1a~1ng agent precursors of formula lS (I). The preparatton of those precursors will be ta~lored to the part1cular ~helating portion and carrier : port~on to be comblned, and especially to the nature of the chemlcal bond between them, e.g. whether the linkage 1s an ester or am~de.linkage, as well as to ?O the presence or absence of other reactiYe ~unctional groups (amino, ~ercapto, c~rboxyl~ 'hydroxy) in either the chelat~ng or carrler portion. Typically~ 1f such other reactive groups are present~ 'they are found in the chelat~ng portlon. In any event, when such groups are present and it ls deslred to protect the~, a step that Introduces approprlate protecting groups can be incorporated at a sultable stage of the synthetic pa~h-way. Pro~ective groups are well known in the ar~ and lnclude t~butoxycarb~nyl for am~no groups, N-0e~hyl-eneacetamido for mercaptans, and N-hydro:xysucclnim-1dyl for carboxyl groups. Acyl or carbonate groups are typlcal1y utilized to protect a1cohol hydroxyls.

~7 ~ ~ 9 ~hen cdrbonate protectlng groups are deslred, the step of ~ntroduc1ng the protect~ng groups w111 ~nvolve reactlng the ~1eohol w1th ~ halocarbonate of the type.
ROCOCl or ROCOBr (formed by react~on of RûH w1th S COCl2 or COBrz~ R typically being loweralkyl). For acy7 protecting groups. the alcoholic hydroxyl 1s reacted with an acyl halide RCl or RBr, R being -COCH3 or -COC(CH3)3. Yet other reaction schemes and reactants 10 will be readi~y apparent to those skilled in the art as will the appropriate means for removing such pro-tective grOups after they have achieved their function and are no longer needed.
In form~ng the precursors of formula (I). at 1east lS one -COOH, -OH, prlmary or secondary amino, amide or fmlde group In a che~ating agent wil1 be bonded to [QC~]9 the hydroph~lic, ion~c pyr~dlnium salt form of a dihydro~
pyrld1ne = pyrldinium sal~ redox carrier.
It w~ll be appreciated that by rQC~] there is ~ntended any non-tox1c carr~er moiety comprisln~, contalnlng or ~ncludlng the pyridini~m nucleus9 whether or not a par~ of any larger basic nucleus~ and whether subst1tuted or ~nsubs~1tu~ed~ the only cr~ter~on there~
for be~ng capacfty for chemlcal reductlon to the correspond1ng d~hydropyrld~ne form CDHC], BBB-penetration af ~DHC] and 1n v1vo oxidatlon of ~DHC] back to the quaternary pyridinium salt carrler mo~ety rQC ].
As aforesaid9 the 10n1c pyr1dinlum salt radio-pharmaceutlcal/ arr~er entity of formula ~IY) whlch ~e5ults ~rom In v~vo oxldat10n of the d~hydropyr1dlne form (TII) ls preYented from efflux from the braln~
wh~le el1mlnat10n from the general circulatlon is accelerated. Radioimaglng of the radionuclide present in the ~locked ~n~ formula tIV) quaternary allows observation-~7~g9 of the tis~r~bution of the loc~lized radlon~clide for d1agnos1s of patholog~ca7 cond~t~ons, abnormal~ties, ets. Subsequen~ly, the coupl~ng between ~he p~rti-cular rad~oactlve specles ~ and the quaternary cdrrler ~QC]~ ~s ~kely met ~olically cleaved which results ~n facile el~minatlon of the carrier moiety tQC 3~
Coupltng between the chelate mo~ety and the quaternary carr~er can be a s~mple direct chemiral bond7 e.g., an amide bond or ester bond, or any other Iike bond, or same can even be comprised of a linking group or function as is i11ustrated in the Examples or the ethylenediamine group illustrated in Schemes

3 and 4. Nonetheless, the bond is intended to be, and is hereby defined as, inclusive of all such alternatives.
Eventual cleava~e of the formula (IV~ quater-nary wlth ~aclle elim~natlon of the carrier moiety [QC~] ~s characterist~cally an enzyma~ic or chemical cleavage, e.g., by an am~dase, albeit any type in bra~n cleavage which ~ght result, whether enzymatic, metabol1c or otherwise, of course remains within the a~t of th1s 1nvent1on.
The many dlfferent dlhydropyrldlne = pyrldlnlum salt redo~ carrler moletles lllustrated for use here-in~elow are merely exemplary of the many classes of carriers contemplated by this lnvention. While the following 11st of carrier classes is not meant to be exhaustive (and, indeed yet other carrler classes are illustrated hereinbel~w as well s in the aforemen-A ~ tione ~ ~ ~ ~ the followingmajor classes of quaternaries and the corresponding dihydro forms are prime examples of the moieties encom-passed hereby:

~2~i78~

(1) For llnkage to a chelating agent having at least one -NH2, -NH- or -OH functional grouplng~
replacing a hydrogen atom from at least one of said functional groupings with one of the ~ollow~ng [QC
groupings:

~C-tNH-alkylene-C-tp , ~ X

Rl R3-8~ NH-OlkYlene-c~D
~o~ ~b) O o o o o eOc~2e~ Na-olkYIene-e~p , ~e+ N~-ol kYlene-e~v (c) (d) ~X ~COCH2C~NH-alkYlene-C~D, R3-C~NH-olkylene~C+p, ~f) C~NH-~lkYlene-C~p , [~X O
H~Rl Ro `R3-CtNH-alkylene-C~p, (9) ~h) or ~COCH2C~NH-olk lene-C~p, ~J~

~2~g~

where;n the alky7ene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro is a radical identical to the corresponding portion of a natural amino acid; p is 0, 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different ; and the Ro radicals can be the same or different; Rl is C1-C7 alkyl, C1-C7 haloalkyl or C7-C10 aralkyl; R3 is Cl to C3 alkylene; X ls -CONR R wherein R and R , : which can be the same or different9 are each H or Cl-C7 alkyl, or X is -CH=NOR wherein R is H or C1-C7 alkyl; the carbonyl-containing groupings in formulas (a) and (c) and the X subst~tuent in formula (b) can each be attached at the 2, 3 or 4 position of the pyridinium ring; the carbonyl-conta;ning group;ngs ;n formulas (d) and (f) and the X substituent in formula (e) can each be attached at the 2, 3 or 4 position of the quinolinium ring; and the carbonyl-conta;ning groupings ;n formulas (g) and (j) and:the X substituent in formula (h) can each be attached at the 1, 3 or 4 position of the isoquinolinium r~ng;
(2) For the linkage to a chelating agent having at least one -COOH functional grouping, replacing a hydrogen atom from at least one of said -COOH group1nys with one of the following ~QC+] groupings:
(a) When there are one or two -COOH groups to be derlvatized:

~2~78!~9 ~C~ HH-olkylene-C~p 0-2'- , ~

R3-C~NH-alkylene-C~p O-Z'-, tl) 8 Ro ~Cocll2c+ol~;ol2yl~n~-l+2~ c~aa-clYYI~n~-c~bo-2-, ( ~v) (~COCH~C~H-olkylene-C ~D -Z'-R3-~NH-olkYlen~-C~p a-z~ , RHl Ro (v) tYI ) C ~ NH-o l ky l ene-C ~p O-Z ' -, ~ O
~Rl H - R3-~HH-ol,kylene-CiD 0 2 tvJ I ) 2 g P
or ~ Co~H2~HH-olkyl~n~ ~D Q-2'-, ~ lx) 9~

wherein thP alkylene group can be stra~ght or branched and can contain 1 to 3 carbon atoms; Ro 1s a rad1cal identical to the corresponding portion of a natural amino acid; p is 0, l or 2, prov;ded that, when p is 2, then the alkylene groups can be the same or different and the Ro radicals can be the same or different; Z' is Cl-C8 straight or branched alkylene, preferably Cl-C~
straight or branched alkylene; Q is -O- or -NH-; Rl is Cl-C7 alkyl, Cl-C7 haloalkyl or C7~Clo aralkyl; R3 is C1-C3 alkylene; X is -CONR'R'' wherein R' and R'', which can be the same or different, are each H or Cl-C7 alkyl, or X is -CH=NOR''' wherein R''' is H ~r Cl-C7 alkyl; the X substituent in formula (ii) and the car-bonyl-containing groupings in formulas (i) and (iii) : 15 can each be attached at the 2, 3 or 4 position of the pyridinium ring; the X substituent in formula (v) and the carbonyl-containing groupings in formulas (~v) and (vi) can each be attached at the 2, 3 or 4 position of the quinolinium ring; and the X substituent in formula (viii) and carbonyl-contain~ng groupings in formulas (vii) and (ix) can each be attached at the 1, 3 or 4 position of the lsoquinolinium ring;
(b) Alternatively, when there is only one -COOH
group to be derivat~zed:

(R4~s ~ ,~
C~ 12 4)niV~ T

~X) tXi) ~L2~;78~

~-C ~- HH-ol kYI ~ne C i~ ~H ~ e ~ NH-ol kylene ~ HH . ; T

(X I I I ) ' tX I I ) ~ C~-~H-olkYIcne-C+~N~

~xlv~

wherein' / is the skeleton of a sugar molecule; niV
is a positiYe lnteger egual to the total number of -OH
functions in the sugar molecule from which said skele-ton is derived; nv is a positive integer one less than the total number of -OH functions in the sugar molecule from which said skeleton is derived; each A in each of structures (xii), (xiii) and (xiv) can independently be hydroxy or D', D' beiny the residue of a che-lating agent containing one reactive -COOH functional group, sa~d residue being characterized by the absence of a hydrogen atom from said -COOH functional group ~n said chelatlng agent; and each R'4 in each of.struc-tures (x) and (xi) can independently be hydroxy, io ~

1~2G7899 -o~Eoldy~

-O~C-:Ikylene-NH1j-C ~ orD', wherein the alkylene group can be straight or branched and can contain l to 3 carbon atoms; Ro is a radical identlcal to the corresponding portion of a natural amino acid; p is 0, l or 2, provided that, when p is 2, then the alkylene~groups ~an be the same or different and the Ro radicals can be the same or different; D' is defined as with structure (xii ), (xiii )~ and (xiv); R1 i 5 Cl-C7 alkyl, Cl-C7 haloa1kyl or C7-Clo aralkyl; and the depicted carbonyl-containing groupi ngs can be attached at the 2, 3 or 4 position of the pyridlnium or quinol~nium ring, or at the 1, 3 or 4 posltion of t~e isoquinolinlum rlng; wlth the proYlso that at least one R'4 in each of structures (x) and (xi) is 15 ~ - O+~-olkylene-NH~ ~) , :

~;7899 -~5-o O ~
-O~C-Ol~Ylene-NH~ct(~N)~J or R

~ -O+C-olkylene-NH~-C ~ , :

wherein alkylene, Ro~ p and Rl and the position of the carbonyl-containing groupings are defined as above; and with the further proviso that when more than one of the R'4 radicals in a gi~en cornpound are the aforesaid carbonyl-containing groupings,~then all such carbonyl-containing groupings ~n said compound are identical (3) For linkage to a chelating agent having at least one -NH- functional group whlch is part of an amide or imide structure or at least one low~pKa primary or secondary amine functional group, replacing a hydrogen atom frorn at least one of said functional groupings with one of the follow~ng [QC+] groupings:

_N~-oll~y~ne-C~OC~ X

Rl lk) : ~ R3-~ NH-alkylene-C~OCH-, :

2~

O O O O
COCH2~HH-olkylene~ OCH-, ~ C-~NH-o~kYIene-C ~ OCH-, Rl (m) Rl~n) o O O
[~ O ~COCH2C+NH-olkY~ene-~OCH;

R3-Ç~NH-olkylene-c~-OÇH-~ R
O Ro R
(o) (P) (~ Ct~H-alk,Ylene-C~OC~! (~x o Rl `R3-~- - N~-olkylene-C~CH-, r~

or ~ COCH2C~NH-olkylene-C ~ O~H-~s) wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro is a radical ldentical to the corresponding portion of a natural amino acid; p is O, 1 or 2, provided that, when p 1s 2, then the alkylene groups can be the same or different and the Ro radicals can be the same or diFferent; R1 is Cl-C7 alkyl, Cl-C7 haloalkyl or C7-C10 aralkyl; R is hydrogen, Cl-C7 alkyl, C3-C8 cycloalkyl, C1-C7 halo-alkyl, furyl, phenyl~ or:phenyl substituted by one ormore halo~ lower alkyl, lower alko~y, carbamoyl~ lower alkoxycarbonyl, lower alkanoyloxy, lower haloalkyl, mono(lower alkyl)carbamoyl, di(lower alkyl3carbamoyl, ~7~
-27~

lo~er alkylthio, lower alkylsulfinyl or lower alkyl-sulfonyl; R3 is Cl to C3 alkylene; X 1s -CONR'R"
wherein R' and R'', which can be the same or different, are each H or Cl-C7 alkyl, or X is -CH=NOR" ' wherein R''' is H or C1-C7 alkyl; the carbonyl-containing groupings in formulas (k) and (mJ and the X substituent in formula (1) can each be attached at the 2, 3 or 4 pos~tion of the pyridinium ring; the carbonyl conta1n-ing groupings ln formulas (n) and (p) and the X substi-tuent in formula (o) can each be attached at the 2, 3or 4 position of the quinolinium r1ng; and the car-bonyl-containing groupings in formulas (q) and (s) and the X substituent in formula (r) can each be attached a~ the 1, 3 or 4 position of the isoquinolinium ring.
Here and throughout this application, the expres-sion "C1-C7 haloalkyl" means ~Cl-C7 alkyl substituted by one or more halogen atoms. Also here and throughout this application, the alkyl radicals, inc1uding alkyl and alkylene portions of other radicals, can be straight or branched unless otherwise specified.
The expression "Ro is a radical identical to the corresponding portion of a natural amino acid" is bel1eved to be self-explanatory. Thus, for example, Ro can be hydrogen, as in glycine; methyl, as in alan1ne;
-CH(CH3)2, as ~n val~ne; -CH2-CH~CH3)2, as in leuc1ne;

-CH-C2H5. as lo ~so1eucine; -CH2 ~ , as in phenyl-alanine; -CH2-C ~ , as in tryptophan;

~ i'l `

2 ~7 ~9 -CH20H, as 1n ser~ne; -CHO~-GH3, as ~n threonine;
-(CH2)2-SCH39 as in methionlne; -CH2-C~NH2, as in asparagine; -CH2C~2-CO~H2. as ln glutamine;

CH2 ~ 3 OH, as in tyrosine; -CH~SH, as in cysteine; -CH2COOH, as in aspartic acid; and -CHzCH2COOH, as ln glutamic acid~ The expression "natural amino acid" as used herein;does not encompass dopa or L-DOPA. Preferred amino acids encompassed by the Ro term include glycine~ alanine, valine, leucine, phenylalanine, isoleucine, methior,ine, asparagine and glutamine.
The dihydro forms [DHC] corresponding to the aforementioned quaternaries are as follows:
(l') for Group (1) above:
O O x ~ Ro ~ 0 H R3-C~-NH-olkylene-C~D , Rl ~ ~0 lo'~ (b') ~COCl~2C~r~ yl~nt-c~D ~ ~ctNr-oll~yl~n~ D , ~1 R
( d ' ) X O O O
~COCH2C~HH-lkyl~ne c~D ' R3-C~NH-oIkyIene-C~
~ Ro Rl - ~267899 O O
Kll- o l ky I ene-~ ~D
C~HH-olkylcne-C~p , ~Rl Ro ~g') ~g") X

H-olkyl~ne-~ +p , ~`R3-C~ NH-alkylene-C~p ~h' ') ~h') O O p COCH2C~HH-o I kY I ene-~ ~D
COEH2C~NH-olkYlene-Ctp or ~Rl Ro ~J ') ~J ") wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro is a radical identical to the corresponding portion of a natural amino acid; p is O, 1 or 2p provided that, when p is 2, then the alkylene groups can be the same or different and the Ro radicals can be the same or different; the dotted l~ne in formulas (a'), (b' J and (c') indicates the presence of a double bond in e~ther the 4 or 5 position of the dihydropyridine ring the dotted line in formulas ~d'), (e') and (f') indlcates the presence of a double bond in either the 2 or 3 position:of the dihydroquinol~ne ring; R1 is C1-C7 alkyl, Cl-C7 halo-alkyl or C7-C10: aralkyl; R3:is C1 to C3 a~kylene; X i5 -CONR'R'', wherein R' and R'', ~hic~h can be the same or different, are each H or Cl-C7 alkyl, or X ~s -CH'NOR''' wherein R''' is H or Cl-C7 alkyl; the . ~ :

~671~9 carbonyl-contai ni ng groupings 1n formu1as (a') and (c') and the X substituent ~n formula (b') can eaoh be attached at the 2, 3 or 4 position of the dihydro-pyridine ring; the carbonyl-containing groupings in formulas (d') and (f'~ and the X substituent in formula (e') can each be attached at 2, 3 or 4 position of the dihydroquinoline ring; and the carbonyl-containing groupings in formulas (g') and Ij') and the X substi-tuent In formula (h') can each be attached at the 1, 3 or 4 position of the dihydroisoquinoline ring;
(2') For Group (2) (a) above:

O O
~C~NH-~lkylene-~ ~p C z~ X ~

(1'~ R3-,C,~NH-olhylene-C~ O-Z'-, COCH2C~-HH-al~ylene-C~Q-Z'- , ~ C-~NH-olkylene-c~pQ

Rl ~111') Rl ~IV') O o o COCH2C+NH-olk,vlene-~ Z , R3-~NII-ol yyl ene-~ ~ O-Z'-, tv I ' ~

~v') ~78~9 O O
C~HH-olkYlene-~ 9-Z'-~NH-olkylene-C~0-Z'- ~ Rl 1Y~

tvll') ~R3-C+NH-alkylene-C ~ 0-2~
0 Ro R3-~NH-olkylene-~ ~0-Z'-(vlll') (vlll") o O O ' eOCH2C~HH-alkylene-~ ~ O-Z'-OCH2~HH-alkylene-~ ~ 0-Z'- or ~RI Ro (Ix'~ ~lx'') wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro is a radlcal identical to the corresponding portion o~ a natural amino acid; p is 0, 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different and the Ro radicals can be the same or different; the dotted line in formulas (i'1, (i') and (iiî'/ iadicates 2 6~ ~9 the presence of a double bond in either the 4 or 5 pos~tion of the dihydropyridine ring; the dotted line in formulas (iv'), (v'3 and ~vi') indicates the pre-sence of a double bond in either the 2 or 3 position of the dihydroquinoline ring; Z' is Cl-Cg straight or branched alkylene, preferably C1-C3 straight or branched alkylene; Q is -0- or -NH-; Rl is C1~C7 alkyl, Cl-C7 haloalkyl or C7-C10 aralkyl; R3 is Cl-C3 alkylene; X ~s -CONR'R'' wherein R' and R'', which can be the same or different, are each H or C1-C7 alkyl, or X is -CH=N0~''' wherein R''' is H or C1-C7 alkyl; the X
subst~tuent in formula (ii') and the carbonyl-contain-ing grouping in formulas (i') and (iii') can each be attached at the 2, 3 or 4 position of the dihydropyri-dine ring; the X substituent in formula (v') and thecarbonyl-containing grouping in formulas (iv') and (vi') can each be attached at the 2, 3 or 4 position of the dihydroqu~noline ring; and the X substituent in formula (viii') and the carbonyl-containing groupings in formulas (vii') and (ix') can each be attached at the 1~ 3 or 4 position of the dihydroisoquinollne r1ng;
(3') For Group (2) (b) above:

~R4)5 ,--~
~R4)~lY T

(x') tXI') 2~39~3 ~HH-olkylene-C~ NH _- `' Ro ` 7/ , ' ~N~ (A) ~v Rl (xll') ~NH-olkylene-~ ~HH ~

Rl (xlll't (A)~v ~I+HH-olkylene ~HH-- ~ or (xlv~ (A)nv ~;oll~lene-~N

(x lv" ) wherein the alkylene group can be straight or branched and can contain 1 to 3 oarbon atoms; Ro is a radical identical to the corresponding portion of a na~ural amino acid; p ~s 0~ 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different and the Ro radicals can be the same o~r different; the dotted line in formula (xii') indicates the presence of a double bond in either the 4 or 5 positlon of the 6~

dihydropyridine ring; the dotted line in formula (xiii') indicates the presence of a double bond ~n either the 2 or 3 pos1tion of the dlhydroqu1noline ring;l l~s the skeleton of a sugar molecule; n~v is a positive integer equal to the total number of -OH func-tions in the sugar molecule from which said skeleton is derived; nv is a positive integer one less than the total number of -OH functions in the sugar molecule from which said skeleton is derived; each A in each of structures (xii'), (xill'~, (xiv') and (xiv" ) can independently be hydroxy or D', D' being the residue of a chelatlng agent containing one reactive -COOH func-tional group, said residue being characterized by the absence of a hydrogen atom from said -COOH ~unctional group in said chelating agent; and each R4 in each of structures (x') and (xi') can independently be hydroxy, -O~-olkYlene-llH~ ~
Al - O ~ C-ol AY I ene-Nlt ~ C

O+e-alkylene-H~

-O~e-olkYlene-NH~ C
~o ;~
orD~, Rl ~

~26~ 9 wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro is a radical identical to the corresponding portion of a nat~ral amino acid; p is 0, 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different and ~he Ro radicals can be the same or different; the dotted line is defined as with structures (x~i') and ~x1~i'); D' is defined as with structures (xii'), ~xiii'), (xiv') and (xiv''); R1 is Cl-C7 alkyl, C1-C7 haloalkyl or C7-C10 aralkyl; and the dep~cted carbonyl groupings can be attached at the 2, 3 or 4 position of the pyridinium or quinolinium ring or, except where otherwise specified, at the 1, 3 or 4 position of the isoquinolinium ring; with the provlso that at least one R4 in each of structures (x') and (xi') is -O+e-Dl~yl~ne~ +D e ~1 -O~-ol kYle~le-HH~ C ~

+e-~lkylene-N~ ~3 Or O O
-O~C-olkylene-NH~C
Ro R

1~67~399 - whereln alkylene, RoJ p, Rl, the dotted lines and the posit~on of the carbonyl-contain~ng groupings are de-f~ned as above; and with the further proviso that when more than one of the R4 radicals In a given compound are the aforesaid carbonyl-conta~ning group~ngs, then all such carbonyl-containing groupings in said compound : are identical;
(4') For Group (3) above:

C+HH-ol,kylene ~-OCRH , ~ x R ~ R3-C+NH-olkylene-C~OCH-, (k~

~COCH2C~NH-~lkylene-C~OCH-, ~jC{-NH-olkylene-~OCH- J

~1 Rl (m~) (n') ~j O ~COCH2C~NU-olkyJer~e c~O,CH-, R3-C~NH-olkylene~ ~ acN-, Rl :

o') . P

1~:67~

C+NH-alkylene.~ OCH_, ~HH-~IkYlene-~OUl-, f9~1 Ro R

Rl :
:

3'j~NH-Oll~ylene-~ofH-~
~r') 3~0~ ~H-:IRYI-n~-e~of~--, (r") .

0~ Ro h or ~s') .
COtH2e~HH-:I l~yl ~-E +~ OCH--, H~R ~ ~
~' ~

~7l3~39 wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; Ro ls a radical ~dentical to the corresponding portion of a natural amino acid; p ;s 0, 1 or 2, provided that, when p is Z, then the alkylene groups can be the same or different and the Ro radicals can be the same or different; R is hydrogen, C1-C7 alkyl~ C3-C8 cycloalkyl, Cl C7 haloalkyl, furyl, phenyl, or phenyl substituted by one or more halo, lower alkyl, lower alkoxy, carbamoyl, lower alkoxycarbonyl, lower alkanoyloxy, lower halo-alkyl, mono(lower alkyl)carbamoyl, di(lower alkyl)car-bamoyl, lower alkylthio, lower alkylsulfinyl or lower alkylsulfonyl; the dotted line in furmulas (k'), (l') and (m') indicates the presence of a double bond in either the 4 or S position of the dihydropyridine ring;
the dotted line in formulas (n'), (o') and (p'~ indi-cates the presence of a double bond in either the 2 or 3 position of the dihydroquinoline ring; R1 Is Cl-C7 alkyl, Cl-C7 haloalkyl or C7-C1o aralkyl; R3 is Cl to C3 alkylene; X is -CONR'R'', wherein R' and R'', which can be the same or different, are each H or Cl-C7 alkyl, or X is -CH-NOR''' where~n R" ' ls H or Cl-C7 alkyl; the carbonyl-conta1ning groupings ~n farmulas (k') and (m') and ~he X substituent in formula (l') can each be attached at the 2, 3 or 4 position of the dihy-dropyridine ring; the carbonyl-containlng group~ngs in formulas (n') and (p') and the X substituent in formula (o') can each be attached at the 2, 3 or 4 pos~tion of the d~hydroquinoline ring; and the carbonyl containing groupings in formulas (q') and (s') and the X substi-tuen~ in formula (r') can each be attached at the 1, 3 or 4 position of the dihydroisoquinollne ring.

~67~99 The presently preferred dihydropyridine~~pyri-din1um salt redox carrier moiet1es of this invent~on are those wherein p is O or 1, most preferably 0;
alkylene, when present (i.e. p = 1 or 2), Is -CH2-; Ro~
S when present(i.e. p - 1 or 2), is ~, -CH3, -CH(CH3)2, -CH2-CH(CH3 12 . -CH-C2H5, -CH2~ , -(cH2)2-scH3~

-CH2-CONH2 or -CH2CH2-CONH2; R1, when present, is -CH3;
R3, when present, is -CH2CH2-; X, when present, is -CONH2; the depicted carbonyl-containing groupings in formulas (a) and (c) and the X substituent in formula (b) are attached at the 3-position; the depicted car-bonyl-containing groupings in formulas (d) and (f) and the X substituent in formula (e) are attached at the 3-position; the depicted carbonyl-containing groupings in lS formulas (g) and (j) and the X substituent ~n formula (h) are attached at the 4-position; Z', when present, ls C2 or C3 straight or branched alkylene; Q, when present, is -NH-; the X substituent in formulas (ii) and (v~ and the depicted carbonyl-conta1ning groupings in formulas (i), (iii), (iv) and (vi) are attached at the 3-position; the X substituent ln formula (Yiii) and the depicted carbonyl-containing groupings in formulds (vii) and (~x) are attached at the 4-position; and the depicted carbonyl-containing groupings encompassed by formulas (x), (xi~, (xii), (xiii) and (xiv) are in the 3-position of the pyridinium or quinolin~um ring and in the 4-position of the isoquinolinium ring; ~ll R'4's ln structures (x) and (xi) are -OH except for the one R4 ~IL2~ 39

- 4 o -In each structure which must be the carr~er mo~ety; all A's in structures (x~l), (xli~) and (x~v) are -OH;, j is the skeleton of a glucose molecule; R ~n formulas (k), (1) and (m) ~s hydrogen, methyl or CC13; and the depicted carbonyl-containing groupings in formulas (k) through (s)are in the 3-position of the pyr~dinium or quinolinium ring and in the 4-position of the is~uino-linium ring; and the corresponding dihydro ~oietles.
Especially preferred dihydropyridine = pyridinium salt redox carrier mo~et~es are the quaternaries of Group (1), structures (a), (b), (d~, (e), (9) and (h);
those of Group (23, structures (i), (ii), (iv), (v), (vii), (Yiii), (x) and (xii); and those of Group 3, structures (k), (1), (n), (o), (q) and (r); and the corresponding dihydro forms, most especially when they conta~n the preferred structura1 variables identified - in the preceding paragraph.
The following synthetic schemes il1ustrate various approaches to the preparation of the sarrier-contain~ng chelating agent precursors o~ fsrmula(I~, to the corresponding carrier~containing chelating agents of formula tII) and to the corresponding carrier-containin9 rad~opharmaceuticals of ~4rmula ~III).
Also shown are the correspond~ng "locked in" qua~ernaries of formùla (IV~ formed ~y ~n Yivo oxidatiQn of the formula (III3 chelates, sa~d formula (IV) quater-nar~es be~ng ~he pr~mary locali~ed materials whose rad~onuclide content ~s:~maged by radiation detection means.
;

~7~

SCHEIIE I

CH2-CHCOOH CN2-~CHcoo(cH212 11H ~IN NH IIH
O~C ;C~O O~C C~O
HO-(CH2) -I
CH2 CH2 --~ CH2 tH2 I IS 9Cc $ $

t~ ch~l~t1n ~gent descrlbed ~n Fr1tYLer~ ,~ A
U.S. P~tent llo. ~1, ~
4 ,~4 ,690) ~O~C~/ COIIH2 - CH2-CHCOCl / ~ ~
SOC12 HH #N
or C-o ~ CONH2 CH2 ~1H2 CH2-~HCtC~2)2-N~
s s ~ o~c r.-o H H l I
CH2 ICHz / S S
~ H H
Tc-99a: ~ertechnet-te /
~nd r~duc~ng ~gcnt ~
e~g. 11~2520~, 1n / reducSlon, t.g.
~1c ~d~ul~ / ~lth H~2520~, 1n b~s1c 1ed1ua CH2-~HCOO~cH212 ~
o NoTcO4ireducln~ ~sent ~IH ~H
S ~ ~S ~ ~-C ~-o C H2 Cj H2 ~7 ~=<CollH2 H H
COO ( CH2 ~2 '~
~ O
~ CO~
oootcH2)2-~

orY 'loc-td ~n~ br~

8!~

SCHE~E 2 N2110C ~_ ~J t~12~2-'H
H2tlCH2CHCOOH N2llcH2~cHcoo~cH2)2 ~ 1-I~ Hz ~H H2 1~2) ClCN2CO~l ¢~CONH2 C~(2 iCHCOO(CH2 );2-N~
l~f IIH ~ ~ CONH2 O-t C~O ~ ~ CH2-~HcootcH2)2-r~ 0 ICH2 CHz ~Cs~ H f~H
S S < , -... O-C C-O
O-C C-O 10 ~ CH2 CH2 9 ~ ~ Cl Cl ,__< COIIH2 ICH2-fHcoo(~N2 )2-~ ~ CO~H
l/H IIH
O~C C~O u1th h~2520 ~n IH2-lllcoo(cN~
~C~z ~CH2 b~s1c edlua S 5 :-- . ,;, O-t C.o H 1~ CH2 1cH2 Tc-99a pertqchn-tetl H H
~nd r~duc1ng e~cnt ~: .9. 1~-2520~, 1n ,~ 4 \~s~1c ~edlua ~ ~ HakO4/reducln9 ~9ent ~,5~

~,~CCNH2 0~o~ COO(CNz)~

O;
~ 5 ~ ~ ~
COIIH
~ 2 COO~CH2)2 H~
X
torl~ loc~d 11l- bre1n ~7~9 SCHE~IE 3 NO C~ ~ ~~H t -OOC SH

31N2 r O t-80C
12 ~ ~I-C~I~SII

~~ NH2 H2r ~ BOC
-- ~ N--C--r~~ SH

1~
~,,COO- ~ - 0~

CH ~ ~ t O O~

SCHEME ~ cQ~t.

N O
t~ I U

7 ~ [~ C sb~

~9 ~3 _ ~ 5,~3--Y

19 h-2S O /b-tC
2 ~ ~ Co~plex of 99'2Tco ~1th 99-T~oi reauctlon of pyr1d1n1uo~ r1ng ~ 1n v1vo ox1d-t10n Qu~lternary for~ o~ r~d10ph~rr~-7~

SCHEUE ~

~ 1R~ RO~ --C~ ~p ZZ \P CHJ
2~

Z3~ ~p~l ~ C--CH3 2!

2~ ~ ~12~ 1P~
H 0~ SH
~1l CH3 H rll 2 -46 ~

SCHEME 4~ C5!11' t, 25 o 17 ~ ~lC~
0~ 1~
o ~ly C-- tH3 26 ~ 99~ _ ~ ts~plex 1~1th reduct10n in ~ o oxld~t10n ~u~ern~r~ ~orGI o-r~d10ph~r~ceue1c~1 'locl~ed 1n ~r~tn ~78~9 ~47-SCHE~1E 5 H2~1CH2CHCOOH 2 2, 2 5 dH2 C2H30H ~IH2 >
HCl ~ O
reduct 1 o~
N (; ~ ~Sth ( 1 ) ~aHCO
, 2 ~HC 20H (2) ClCN2~0Cl H21iCH2,CHCH20H
HH IIH ( ~H2 O~t ~0 3 ,CH2 ,CH2 Cl Cl ~
~2 \ : ICH2~ CIHCOOC2H5 . \ NH NH
~CSH~ \ LIBH4 O-C ¢=O
Cl H2 CH2 Cl Cl ~ 2 , C 2 CH2--CHCH20H
hH aH hH NH 4 O~C C~O ~'2CO3 ~ o~c c~o CH2 C.~2 CH2 CH2 S S S S
o.c c.o h h ~3 34 J,bro~o~cet,yl chlor1de ~_~ COh 2 CO$1H
,CH2--,CHCH20COCH2-11'~ H2--CjHCH20COCH23r hH HH ~ HH HH
O~C C~O 'r < O~C C~O
C~2 SH2 ,CH2 `CH2 S S S S
H H H H
~6 35 :

: :

~Çi7~

SCHEME 5, con't COhH
Cl/f CHcH2ocotH2-h~ ~ =~COHH2 S~H HH \ Cl H2 CHCH20COCHz-l~ >
C O ruduct10n, ~.g. ~11th NH ~/H ~=~

1~ N et1un ~ ~H2 tH2 J6 N b \ Tc~9~ pcrtlchnetcee 252~ 1n gst1c NrJTco4/reducln9 rgent \;edluu O

F:~ CONH2 tH20 OCHz-ll~
v 1 ~d ~_,COHHz CH20COCH2-~10 ~cr- 'locl~td 1n- br~1n 6~9~

SSHE~E 6 N2~lcN2clHcooc2Hs ~N--CHCOOC H
XH ~11 II-IICO3 HH2 ~ 2 5 2 (Z) ClCH2COCl O~C C~O

¦~L.

HH dH ~ CH2-- ,CHCOOC2H5

5~C C-O 3 O-C C~O
S :, h ~ : o c c o \chl or~ 1 \

CH2--CHCûNHCHOH
#H IIH
O~C C-O
CNz CHz H H

- 5 ~ -SCHEME Ç, con't.

CHr ~CHC~HCHH CC13 ~H ~H n1cot1n1c c1d ~H ~H
DCC ~C C-O
CH2 e~2 ~ C, 1~2 CH2 S S S
il H U b CH2--CHCOIIHCHOC~H3 NH # H O

S S

Tc-99u pcrtecbnet~te ~nd rctucfng 6gent, ~ reduct10n, e.g.
~-9~ ~2524~ / ~1th N~252~ ~n ned1u~ ~ b~slc ~et1u~

C~2- ~ C H C O 1~ H C HO
NoTcO4treduclng 09ent ~H ~ 0 0 J~ CH2 CH2 0 ~6 COI~HCHOC~CH3 1n v1ro oxl~t10n 0 c~ucu~o~
or~ loc~cd 1n' ~r-1n CCla ~67~ 39 SCHEnE 7 HOOC~N--CliCOOH C2H50H C2H$00C&H--CHCOOC2H5 IIU2 ~H2 IICl ~ hH2 NHz (2,a~ nsucc1nlc ~c1d) ~Ig I ) Cl tH2COC1 (2) ~ C25~-~C~ ~ ' C2H500CCH--CHCOOCzH5 ~CH--~ O~C C~O
O-C C O (I) IIN3S S
CH ' < (2) ~ O-C C~O
H ~ 51 SZ

,CH20H CH20C~) ~'5~ \~C~ rl1cot1n1c c1d ~C/ \C~
~CH--CN =~ CH--CH
IIH bN NH UH
O-C C-O O~C C,~O
CH2 CH2 ~ H ~ H
b h d H

SCHE~E 7, con ' t .
~H20~ SH20~ ~CH31 ~C~ \C~ O /M\ O
~CH C~ 3 > CH CH
UN aH qH HH
o c c o o c lc o CY2 CH2 SH2 ~, H2 tl 1I N H

Tc-99- pe rtoc hn~ t- t~ /
and r~uc1n~ nt~ reduct10n, e.9.
n~ 2s2o4~ ~n~ ~1eh l~52524 1n ~ 1 C ~ d 1~/ ~ ~ i l c Jb d 1 ~

~H2~H3 D S NnTCO4/redUCIng ~C~ \C4 ;~ ~-- TH--NH
o~c c-o =~ j-- C,H2 CH2 C~ H h \ 1n v1~o ~t10n q , .
~S

CH20C~
: ' ~or~ ~locked 1n~ ~rJ1n scllell~ 2 H2~ tcHz32-~H H2"~Coo(CH2~2-î~?
Il 2 ~ H2 1- COIIH2 (3,4-d1~ o~n~olc ~Id~ 60 ~1 ) N~HC03 , (2) ClCtl2COCl Cl CH2CH~l~ coO iCN2 )2~
~CSN~/ 2cl COWH2 ~/

~CSCr2C#H~COOtCH2tz~W~ t' 62 IIHCCH2SC~ CO~H2 N5CH2~H~Coo(tH2~2-~
HllCCr25H COHH;~

~x~

SCHEME 8, con't, HSCH2UIH~ coo~caz )2-~
IlHtCI!25H C~H2 reductlon ~.9.
\~11th If-2520~ tn \~s1c ~ed1u~
1~-990 v~rtcch n c t ~ t c ~ f d ~ - O ~ 2 2-9- #~25Z~ HSCH2CHH--<O)--C~ 2J2 1 1n b~s1c >~
~s~d1u- ItHccH2sH

~aTcO4/reduclng ogent o O

C ~

COI~H_ ,~COHHz ~:OO~CHZ)2_~ CICH2~2'1/~
tor~ ~1ock~d 1n- br~1n fiS ~5 ~:

:: :

778~
-5~-SCH~

C~CH~ ~ 113t ~H3 C~l(NOH)CCOOC2H5 1~2/PtO2 Cl-H3N C~2CH~C2H5 HC~/C2H5h~' hH5~C~^

~C2H5 70 68 ~ 70 PYrldlr~ CH H
H3CI Ij,C~3 ~COHH~

~33Cc~ 3 ~ \ LIAIH4 NaBH4 \~
, ~HH2 ~CH2~12 H H LlAlH4 hH HH
H33~ ~ H C~l H;~ 2 : ?3 ~4 ~HC I
dlhydrochlorlde solt of 74 ~2~71399 SCHEME 9, oon~t~

~HH ~ ~,C~I2HHC ~) I~;C~ It~ ~ 1~ 0~ H C ~H2 ~H~CH
16 H3C ~H SH--CH3 ~¦,CH~SI

~
NH ~H
H3C ~ ICH2 CIH,~ CH3 H3C ~ IH SH--CH3 Tc-9~a Pertechnetote and /
reduclns r~ent, e.g. ~ r ~uctlon, e.s.
Nn2S204~ In bOSIC ~ ~ th NC2s24 medlun / ~ In boslc medlun ~rlTcO4/rc~ C~no ~ nt ~CH2HHC~

H3~ 3~ 3~= ~N

o~ldatlon H IC>c ~ Z ~ HC~3 CH2NHC~ X-~onn nlocked In~ braln 1~6'7f~

SCHEME lQ

~2HCH2~HcOoH C2H50H H2NcH2~Hcooc2~H5 hH2 ~ h~2 ~IAIH4) CH(HOH)CCOOC2H5 Nlth LlAtH4 H2HCH2hHcH20H
69 ~ 31 h3C~3 31-- ~3~ ~h;
68 H3C/~S CH3 1LtAIH4 ,~CH20H
N N ~ _~ CN20H
3C~S S~ CH3 NH HH
H3C CH3 LIAIH4 > H3C~CH2 ¢~CH3 71 H3C ~H ~H CH3 ether ~H-HCI NH-HCI

\ C CH~ CH
H3C ~ SH S~\ CH3 Blq ~26~

SCHE~lE 10, c~n't, ~_~ CH20H ~1 ~CH2~
qH NH ~ ~ CW5J ~ HU aH
H3C~H2 ~,~CH3 ~ H3C~C 2 ~H~CU3 H3C ~H ~H C~ 16H3C ~ ?~H S~ CH3 ~ICH3~ &H3 ~C~20C~ 1~
NH HH
H3C ~ C~ H2 t 3,CH3 Tc-9~ Per~echnetate /

s I C

N3~ ~) H3~ ~ CH3 ~{~ X

~onil ~Iccked In' br~ln

6~9~3 ~CHEIiE 11 ~C ~
~ C>[~S--S~3 ~8 1N~BH4 ,G~
H ~ S--S~<CH3 18rC~2~0NH2 ~COH~
H3~ S--S ~C~

tlH CH2N~12 H3~SH 1 HO-~ ~ (~ CO~

91 ' ~%~;7~9~

SCHEM~, çon "~ .

H~HCH2~H2 i~5H i~ H3C CH3 : g J,'i,3, ~ H'CH3 f HH HcH2cH2HH
3C ~ SH ~ CH3;
H3C ~ ~H3 ; /

~ 111 th Ha25204 Tc-9~m Pertechnetate / I Jn baslc ond rHedaus2 ~ o~ent / I redlu~
~ boslc medlu~
: ~ /
~ NoTcO4/
Complex wlth reduclng CH3 tecnnetl~ redox asent f~ O ~--H
~ystem ln reduc ~ ~ ~ _ NH H`CH2CH2HHC ~/

H3C~ C1~2 ICH~ C

~ ~ n H3C SH 1H C~3 Oua~er~ary on~ of 94 ut¦cal ~2678 N2NCH2~CHC~Oc2H5 ~1) N~ CH2--CHCOOC2H5 N1~2 (2) ClCH2CaCI NH NH
' ' ~ O~C C~O
C.H2 CH2 ~I Cl !~

~ ~ CSHu CH2--CHCOtlH2 NH3 CH2--CHCOOC2H5 HH l/H HH NH
O~C ~0 < O=C C~O
C~2 Ctlz C 2 CH2 ~H 1H S S
42 O~C C~
LIAIH4 (~ ~) 4, pl2 ,cHcH2HH2 C112--~CHCH2N112 NH HH HH HH
0~ ~C~O ~/or ~H2 CH2 CH2 ~ CH2 CN2 SH SH SH ~ l;H
g7 g8 ~6713~3 ~CHEME 12. cun't.

CH2 CHCH2HHC~
- CM2--CHCH~hH2 5~ ~ H
iiH IIH ~ ~ O~C C~0 O~C ~ ~ ~)J C,U2 ,CH2 97 ¦CH31 CH3 ,CH2 ,CHCH2NHC~,) ~_ o c c o CH2 sC,lH2 ~ 100 Tc-99m Pertechnetote / reductlon, C.D.
ono reouclng o~ent,~ ~Ith H2S24 e.9. Na2S204, In / In baslc ~aslc ~e~d~ ~I n~dl r _l~c_ rèdoTcc04/ CH;~ CllCH2'1HC
a'"3 o~ c o 102 CH2HH ~ ~ 101 :
S~~S
$~ CH3 103 CH2HH~) X~
~orm '~ocked In~ braln ~2~7~1 SCHEME 12. CQn't.

rj~2 _ ICHCH2HH~ ~N3 HH HH
CH2 ~H2 C~H2 tH2 SH SH

/

Tc-9~ Pertechnetcte /
e.s. Na2S2~,~n ,;~ t~lth Na25204 baslc medlu~/ ~ tn~ slc L/

NCTCO4/ ~H3 s~ radenln9 Ctl2 ---CHCH2HH~
NH NH
\_ C,H2 ~H2 o N,CH3 CH2 CH2 CH2HHC~ SH SH
1,07 1~6 loxl~an YCN2HH~ X~
~or~rocked In' bra~n ~i78~

~ME 1~

~2HCH2C~HCH20H t-butyl chloro~r~te t-BOC-HHCH2CHC~20H
NH2 HH-t-BaC

Il) t~utyl llthllm ~2~ IC 2~H2H
tH2--CHCH20CH2CH20H ~ t-Bl)C-NHCH2CHCH20CH2CH20H
NH2 NH2 HH-t-BOC
~ 110 (1) HQHco3 ~, (2) CICH2COCJ

CH2--~HU120CH2CH20H CH2--CHCH20CH2CH20H
NH HH ~ NH NH
~ C~ SHa O~C C~
CH2 CH2 - - ~ CH2 ICH2 Cl ~I S S
O~C C-O
112 ~ ~

~ NQ2C3 NH NH
0~ C~O
Clt2 CH2 SH SH

gL2~i~`8~
-6S;-SCHEME 13, con't..
~CH2 CH20CH2CH20H CH2--CHCH20CH2c~2oc NH ~H O HH HH
O~C EQO ~ O-C C~
~H2 CH2 ~ C~ ~ CH2 I~H2 SH SH ~ SH SH

CH2--CHCH20cH2cH2o~H3 o-c C~O
CH2 Ctl2 SH ~H

a~d reduclng o~ent, / ¦ reductlon, e.g.
e.9. H~2S204, n ~ 111th Na2S204 ~aslc ~edlu~ ,~ndlamlC

N~TC04~ _ P l~CH3 , CH2 CHCH20CH2CH2 OC~

CH20CH2CH20C~ SH SH
118 1l7 ~OXI
p CN20CH2CH2~) X-ror~ ~rocked In~' br~ln 8~51 OH ~ ~ H5 ~2 2 53,~1~1n~benzolc ocld) 120 59 (l)H~HCC3 ~2)CICH2C0~

(~SC~C2~5 ~ c~ ~c2H5 122 ~CH2S~ nH~2CI

¦ HH3 HSC~ ~HH2 CC~SH
~3 ¦HaBH4faCetIC ~cld HSCH2Ct12~ ~C~H~
H~C~SN

- 6 i -S~H~ 14 . c~n ' t t~ 2HH~t~ HSCH2CH2NH~ CH2NH
2SH ~lHCH2CH2SH

HSCH2CH2HH ~H2NHC~ 1-126 NHC~12CH25H
To^99~ pertechnetate/ re~uctlc~7, e.g.
~nd reduclns Qsent,/ ~Ith Ha2S2~4 In baslc / In baslc ~edlum ~5~ S~ ~aTcO4/ NSC~2C~1%Na~CH2NH~
reduc I ng asent HHCH2CH2SH

-NH~

o ~s~ s~

~ H
cH2-HHc~) X

rorm'locke~ la~ ~raln H2~COOH CICH20Cl CIU~2~11~0H

S9 NH&CH2CI
S~C12 1 te~r~bu~ylannonlu~
borohydrlde : f , q CICH2ÇHH--( O)--COCI . NCI
CIC~CICl~OH H6~CI 131 132 ~C~2CI

l ~

~CSCH2CH~OH 2 3 ~HSCHzCNH ~ CH20H

133 0 0~ Nr&C-25 3 ~1 ~ ~tOO~

~, ::

NSCH2TNH~ OH Oe~ 1~ ~ ~ HSC-2PH ~ CH20~ :
6ÇCH2SH 136 N CC_2~1 13S

~2~7~
~9 SCHEME 15, con'~.

reductlcn, ~,9 HSSH2~(H~CH20~ HSCH ~N~tH2~

137 NH~Ctll25H

Tc~ Per:ec~ \ / hoTcO~/reduclng agent ond reduclng rJgent, e.s.
Na2S204, In baslc ~IUD

?s:?

~) ,CH3 138 CH2~

n 0~

tll2o~) tor~ ~locke~ Ina braln ~2~8~9 ~L~Ç

ethYI llthlu~
2~CH2oH (2)1CH2~H20t~ ~, 02~CH20CH2CH20H

~3,4-dlnltrobenzyl clcohol~

1Sn/HCI

ClCH2~i~20U~2CH20H ~ 2~H20CH2CH20H
~CH2C1 2 ~SNC
~ , ~SC1~2U~H~CH20~H2CH~OH I~SCH2CHH~ CH2CH2CH2~
Na2ca3 CCH2SH
d~jCH2S~ - ~ ~ 145 ~44 1 (~C0~P

~H3 ~ 16 HStH2~N~ CN20CH2C1~20C~> ~ ~ o N
PIHCC112SH I HSCH2CNII~ CH20C~2CH20C~
b ~ HH~CH2SH ~ 145 g7 ~ ~ _ ::

~78~

SCHEME 16, COn't, HSCH2LI~ CH20CH2CH20C~
NHCCH2SH l~

\ Tc-99n pertechnetate reductlon, e.~. I \ ~d reduclns ogent, ~Ith Ho2S204 1 \e~9~ Na2S204, In baslc ~ J ~;

NQ~CO4f 1l O H.CH3 recucln9 5 ~5 HSC112CHH~Ul20cH2cH2 OC~ 0~
NH~CH25H ~) P NCH3 C~OCH2CH2 OC ~
/

ox~,a,7/

15~ ~

SH2oc~2cH2ol~ x-~orm ~Iked In~ braJn ~2~9 ~Z

~ dl~tert-butyl) dlcorbonote ~
H2H~CH2~t~ _~ H2N ~CH2NH-t-BOC
1'~2 #H2 (3,4-al~lnoben~ylGlne) 152 ClCH2COCI
~ 'St~ ~' ~
r--~ O G
~0)--~SCH2~ffH~CH2HH-t~ C CICH2CNH ~ CH2NH-t-BOC
HHCCN2SC~ HH8CH2CI

¦ ~1) Ha2C~13 J~2) trlr~uoroocetlc ocld HSCH2CHH~HH2 (~ o 16 HSCH2~H~ CH2HHC~) t~c~12sH ~156 HH~CH25H

~¦~tH~l HSCH2~NH~C ~) 3 157NH~cH~sH

æ6~s~

SCHE~E 1" con't.

HSCH21~1H~CH2HHe~ tdhUCtl S'Oe;9 ~ CH2NH

157 ~ 158 \Tc-99n Pertechnetote cnd redcclns ogent, \ e-g~ H2S24~ in / NoTcO
baslc ~edlua /reduclng ,~ osent 0~

N'CH3 CH2~H~ ~

Jn ~Q
~¦ cxldotlon o ~ ~CH, 160 CH2HH~ ~ ~ X

~ ~or~ ~loc~ed In~ braln ~26~78~9 CNCH2COOH + H01~ DCC _ ~ CNCH2C00-N~

NH NH HH NCOCH2Cll 3 ~ C C / 3 + 167 ~ 3 \ C I ~ tH3 H3C/ ~S--S CH3H3C/ S--S CH3 ~8 168 I

~LIAIH4 NH ~NCH2CH2CH2NH2 H3C ~ ~ 2 ,CH,~ CH3 H3C ~ gH gH\ CH3 O O

(~ O (~ ~ C C~
16 H3C~ SH SH CH3 CH31 /CH3nO2 CO~169 ~ ~NH~CH2)3-N NH
CH3 H3C ~, 2 CH,~ CH3 CH3 H3C ~ S SH~ CH3

- 7 5 -SCHE E _ 8, con t.

~ ~ , ~ reductlon, e.g. O
r ~ ~ NH(CH~)3-N NH w~th N2524~ ,ju~
N~ H3C ~CIH2 CIH,~ CH3 In oaslc medlum ¢ ~ `NH(CH2)3-N NH
CH3 H3C~ SH SH CH3 CH3 H3C~ ,CH2 C, ~,CH3 ~72 NoTcO4/reduc l ng /
Tc-99m Pertechnetote ana ~ ogent /
reduclng agent, e.g. In ~o2S204, In bcslc I /
meolum 1 /
/

Complex wlth technetlum, redox system In reduced form L vlvo ~ oxldation Ouoternary form of rodloPharmùceutIcal ~locked In~ braln :
:

~L2~

SCHEME ~

Cl-H3N~C~12~CHC00C2H5 ClCOCH2CI -~ NH MH
NH3~CI- O=C C=O

Cl Cl ¦ ~ CDSNa NH ~NCOOC2H5 NH NH
O=C C=O O=C C=O
CSHH2 gCHH2 < NGOH CH2 Cl H2 4 175 O=C C~

~,CONH2 ~ 1CH2CH20H ~ ~CONH

CH2CH~OH

175 ~ 176 ~ ~CONH2 ,CH2 OOC -- I ~
NH NH
O=C C=O

SH SH

Ei7 SCHEME 19, Con~t.

~J 1- reductlon, e.g. ~f N wlth No2S204, In N
CH2 boslc medlum ~ CH2 CH . ~ : CH2 ooc ~ doc NH NH NH NH
O=C C=O O=C C=O

SH SH SH SH
3 \ : 4 ~lnue 05 In Scheme~/

;

~6~

SCHE~ ~Q

cooU tOOH
CICOCH2CI > ~) CO CO

Cl Cl (~ COSNo COON )~ O COOH
Hcr~
NH NH ~ NH NH
CO CO CO CO

,~ CONH2 179 COOCH2CH2N~

175 ~ HOCH2CH2-1~ >
I~ CONH2 NoOH / INH NH
176 ~ CO CO
~COOCH2CH2N~ CH2 CH2 ~ CONH2 CO CO

CO CO
CH2 CH2 cnntlnue as In Scheme 8 > 66 SH SH

~C00-N ~C~0NHCH2CH20H

CH2 CH~ D~E CH2 CH2 I ~ 179 S S
co co : co c~o 1 PB r3 CONH2 CONHCH2CH2Br N~ ~) NH NH
~ co co BrCH2CH2NH3Br~ ¢H2 CH2 181 ~ , s s co co Br~ ~C0NH2 , ~C0NH2 >~-~NH2 ~ON~J ~C0NHCH2CH2Nt~
C~2CH2~H3Br ~ Br ~

co co 179 ~ ~83 ~ CH2 CH2 co co ~2i~

- 8 0 -SCHEME 21 con t ~C~NII~N2CN2N~ ~N~2~N2N~ -NH NH ' NH NH
CO CO CO CO

CO CO

Tc-99m Pertechnetate / reductlon e.s ard reduclng asent ~ ~ wlth Na2S24 In e.g. Na2524 In / baslc medlum baslc medlum /
' ~=~CONH2 o~HcH2cu2N~=~
NaTcO4/reaucIng asent NH NH
o ~ CO CO
S Tc ~ CH2 CH2 N ~ ~ SH SH

CONHCH2CH2N~

vlvo Idatlon 0 S Tc N N
O ~ O

CONHCH2CH2i~ X

form ~locked Jn~ braln i7~

SCHE~1E 2?

N113 ~ ~OOH

RH MH : NH ~H
CO ~CO 178 CO CO
CH2 ~CH2 ~ CH2 CH2 188 SH SH
CO CO
~ O
~, HOlo~J

:

~--( n COOCH2CH2N+~) COON~
(O~ _,~ COIIH2 /~
~ IJocH2cH2-N~ 1-NH RH

CH2 CH l I

SH ~H
63 18~
:

: ~I contlnue os ~n Scheme 8 6G ~ :
' ~2~39~

,CH3 HH <N CH2NH2 O NN tH2NHCO
H3C ~CH2 CH~, CH3 ~CoOo~l H3C~C~2 CH,~CH3 ~ I I ~ I r~ l I ~
H3C SH SH CH3 CH3 H3~, SH SH CH3 74 17 ~ 76 tOOR ~ ~

~tOO~

74 ~ 191~ 76 76 contlnue os In Scheme 9~ 79 ~678~

NH NHCH2NH2 ~ N CH2NH2 H3C ~ CH2 CH ~ ~H3 + CH3-C-CH3 ~ 5 -,C C - S
H3C / SH SH \ CH3 H3C CH3 H3C CH3 ~4 ~ ~ 192 ,17 or l91 :' : NH NH ~ ~ CHzNHC
: H3C ~ ~ 2 ~ ~ CH3 ~ (2~ H2S ; H3C I ~H2 CHz ¦ ~CH3 H3t SH SH CH3 H3C CH3 H3C CH3 ~ I
, contlnue os In Scheme 9 ~ ::
: : : : :: : :

:: : : : :

~ COOH HO-N ~ ~ COO-N

NH NH ` > NH NH
CO CO 178 C0 CO 1~9 CO CO CO CO

SOCI2 ~ NH3 COCI N ~ CONH2 ~NH ~NH NH NH
CH2 CH2 CO C ~ 194 S S
CO CO
CO CO

H2NHC ~ ~LIAIH4 NH NH ~ 00~ N.NH7 C~2 CH2 126 ~ 3 - NH NH
CH2 CH2 CH2 CH2 ~124 SH SH
contlnue~ as In Sch~ '4 ~ 129 ~, CONH2 ~ HO-C-CH2Br --~ ~ CONH2 P8r3 ~: ~ CONH2 C=O
~; ~ Br 197 CH2NH2 CH2NHCOCH2-N ~ Br~
H3C~~ N ~ C ~ 197 - > \ C ~N ~I C ~ CH3 ~ ONH2 S ,C C S S C C--Sg I ~1) HsCI
~ (2) H2S
- ~ CH2NHCOCH~-N~
NH NH ~ Br~
3 \ C CH~ CH3 CONH2 H3C ~ SH gH \ CH3 i99 ~:2~7~

SCHE~E 26, con't.

~CH2NHCOCH2-N~
NH NH
l l Br~ CONH~
H3C ~ C~H2 ~ ~ CH3 L

H3C SH SH \ CH

\ reductlon, e.g. wlth \ No25204, In baslc Tc-99m Pertechnetate \ medlum ond reauclng ogent, e g- NC2S24~ In boslc medlum O ~ CHLNHCOCH2-N~) H3C ~ CH3 ~ cl~ H3C ~ C~2 CU ~ CH3 CO~H2 CH2NHCOCH2-N~) ~ 201 CONH2 200 I~VIVQ
~ oxldatlon H3C ~ N7 ~ ~ ~ CH3 CH2NHCOCH2-N~) X-form 'locked In~ broln 3L26713~9 CH2NH2 CH2NHCOCH28r 3C~ ~ ~CH3 ~ BrCH2CC1~ 3 S I ~< ~CH3 ,C~ C CH H3C CH3 H3C CH3 H3C tH3 H3 3 ~ N~

CH2NHCOCH2-N~ Br~
3C~C--N H--C~ 3 CONH2 continue ~s In H C~¦ CH CH2 I CH~
202 ~ Scheme 26 S C c--S

l9B

' 78~

SCHE~

C CH3L1~ 3 \C/ 2 _~ H3C ~ ~NHZ

~Ac CHOAc 204 CH
204 ~ CHO CHO ----> ~CH~IC~H
205 3 ~ C / \C ~ CH3 H ~ / ¦ [5/1 ~H3 CH3 ~ CH3 ~1 ) N~8H4 ~ ~2) H~

CH2CH2NH2 ~1 ) CH3N02 CHO
H2~C CH2 < ~2) LIAIH4 H2~C~H2 3 ~C/ ~C~CH3~ 3C~c/ \C~
H3C/ ¦ S ¦ ~CH3 H C~¦
I`S S~
CH3 CH3 C~13 CH3 2_8 207 ¦ ~,COON~

CH317 H3C~ ~CH3 ~H Nll I :

2Q9 ~ ~

SCHEPIE 28. con't.

H3C~ ~CH3 HsClz/H20 3 \ f 3 ~CS--,C~ CH3 ~ /CH2NHC,oCH3 CONHCH2CH2 _~ ~ CONHCH2CH2--~

CH2-NH~ ~ ~ 1- CH2NH~CCCH3 N~120H

~HCO ~) 1-H3C~ NH NH~/ 3 H3C ~ CH3 Ho,N CH3 H3C N~OH
Tc-99m pertechnetGte and reduclng Ggent, / 211 : : e,g,~Na2S204, In /
boslc medlum / reductlon, e.g.
: : : / ~ wJth N2S24~ In , boslc medlum N ~CH3 CH2cH2NH
ComPlex with technetlum, NoTcO4/reduclng ~ H
redox system In reauced agent H3C~" NH NH~ /C 3 : form H3C ~ ~ ~ CH3 213 Ho,N CH3 H3C OH
1 ~ v~vo oxldatlon QuGtern~ry form of rodloPharm~ceutlcal 214 ~ ~
~locked In~ broln ~ ~ ;

:

~2~
- g o -O O
Cl-C-C-Cl ~ NH2CH2CH2NH2 ~ C - Cg NH NH

~H2 CH2 : 215 (from a mlxture : : O ~ ~ roducts) CO-N ~ 1-H2N NH ~ ~ ~ J o ~LIAlH4 CH3 \reductlon, e.g. HH2 H2N
\ hlth ~a2S204, In 216 ~ baslc medlum Tc-99m Pertechnetate and reduclnq cgent, : e.s. H52S204, In \ /~~~~~~~~\~ , bcslc medlum ~ H~N NH
ComDlex wlth technetlum, NoTcO4~reduclns ~ C-NH NH
redox system In reduced agent form C ~ ~ N~

¦ In vlvo : ~ oxldatlon Oucternory form of radlophormoceutlcal ~locked Jn~ broln ; 220 .

Thus, Scheme 1 above 11lustrates a typ1cal synthet1c route for compounds 1n whlch the llnkage betwe~n the carr~er 3nd chelate portlons ls through a -COOH funct~on ~n the chelat~ng agent. In the f~rst step, the ~fcohol reactant can be represented generally as ~O-Z'-~ where~n Z Is C1-C8 stra~ht sr branched alkylene; ~n the second step9 the depicted reactant, nlcot~nam~de, could be read~ly replaced with picolinam~del, ~son~cot1namld~, 3-~ulnolinecarboxamide, 4-~soquino-l~necarboxam~de or the like. (3-Quinol~necarboxamide and 4-isoqu~nol1necarboxam~de can be prepared in known manner, e.g. by treating ~he corresponding acids with a~mon~a. ) Other process v~r~at~ons wil l be apparent to those skilled ~n the art, part~cularly from the A~ ~ p~ ~q~ ca9~o~ ~o e afo~ ~ 9tG~oned International One such alternate approach to Scheme 1 is depicted in Scheme 2. In the first step of Scheme 2, the alcohol reactant (prepared by reacting 2-iodoethanol with nicotinamide) could contain a shorter or longer alkylene bridge (C1-C8) than shown and the pyridinium portion could be replaced with an equivalent pyridinium carrier, prepared in analogous fashion. Thus, for example, in the first step, an alcohol of the formula CONH CONH2 ,~v~ CNH2 X~, ~ X~ or ~ ~ ~-(CH2)nH
(CH2~OH (CH2~noH

25 where~n n ~ 1-8, preferably 1-3, can be reacted with 7 or other -COOH-con~a1n~ng chelating agent or pre-cursor thereof. Alternatlve~y~ an alcohol of the formula ;
: (prepared by react~ng n~cot~nfc acid with:1,2-propylene glycol ln ~he presence of d~cyclohexylcarbodf~mfde) or a posltlon ~somer or homologue thereof or correspond-~ng der~vatiYe o~ a quinolineca~boxylfc acid or an isoqufnolfnecarboxylic acid can be quaternized. e.g.
by react~on wfth methyl ~odfde~, and used in place of the alcohol reactan~ shown ~n Scheme 2, As yet another varfat~on, bro~oglucose can be reacted with nfcot1Damfde, p~co1 ~nam~de sr ~ssnicotinamide or ~p-proprfate qu~nol ~necarboxam~de or isoquinol ~necarboxa-m~de to afford a start~ng alcohol of the formula X~ X

~ Br~ HOCH2 HOCH

H ~ OH ; HO ~ H HO ~ H
OH OH
which can be used ~n pl~ce o~ the alcohol reactant used fn the f~rst step of Scheme 2. Stil7 other 6~89 v~rlations would 1nclude reacting n~cot~n~c acid or other sultAble pyrid~ne-r~ng containing actd with ~n appropr1~te dl- or polyhydroxy compound such as ethylene glycol, propylene glycol 9 lnositol or a simple sugar, l~nk~n~ the resultant ~ntermed~ate v1a its free hydroxy group(s) to th~ c~rboxylic ac~d function of the chelat~ng dgent or the precursor thereo~, and then quaternlzing that ~ntermed~ate.
Sche~es 3 and 4 above are ~llustrative of the type of procedure util~zed to prepare compounds ~n whlch the l~nkage between the carr~er and chelate portions ls through ~n -HH2 or--OH function in the chelatlng agent or precursor thereof. The activated ester o~ n~cotin k acid, 1~, can of course be replaced with ~nother açtivated est~r of that or a similar pyridlne-r~ng contatn~g acld. Equivalent actlvated O~
. esters, e.g. an ester in which the -~ is replaced with O

~ or ~ N02 (espec1~11y p~nitrophenyl~, w~ll be apparent to those skilled in the art. The 20 preparat10n of sllch esters proceeds according ~o known procedures, e.g. by reacting the acid chlor~de or ~nhydride or the actd ~n the presence o~ DCC with N- hydroxy-succin~mide or other alcohol r then quaternlzing the product~ e.g. with me~hyl iodide or dimethylsulfate.

, -g4-Scheme 5 illustrates ~nother possible approach when the 11nkage between the carrier ~nd chelate portions 1s through ~n -OH funct10n in the chelatlng ~gent or 1ts precursor. The flrst step 1n th1s sequence 1s descrlbed 1n Fritzberg U.S. Patent No. 4,444,690;
the resultan~ ethyl ester 39 is then reduced to the correspond1ng alcohol, us1ng an Appropriate reduciny agent, e.g. I~AlH4. The reduct~on thus Introduces a -CH20H funct~on ~n place of the ac~d func~ion ~n 10 7. Other -COOH containing chelatins agents or their precursors can be si011arly converted to the corre-spondins -CH20H containlng compounds, wh~ch can then be derivat~zet to the carrier-~ontaining ~oieties ~s generally~descr1bet hereinabove. One such deriv~-tlzat~on ~s shown ~n Scheme 5. The conversions 3~ ~ 3~-~33-~3~4 parallel react~ons shown in Scheme 2 hereinaboYe as we~l as in the Fr~zberg patent.
The carr1er-cont~fn~ng 00~ety can readily be ~ntro-duced ~nto the structure after obta~n1ng 3~4 by ~
v~rie~y of ~e~hods, e.g. by use of the act1vated quaternized ester 17 used in.Schemes 3 and 4 or other activated ester;or by reaction with bromoacetyl chloride, followed by reaction with nicot;namide, isonicotinamide, 3-q~inolinecarboxamide, picolinamide, 4-isoquinolinecarboxamide or the like to form 36 or similar derivative. Subsequent reduction to the dihydropyridin~ form ~s dessribed herein and in A b/~ca ~ 7 ///o~ ~0~3/03~G~
International Appli~-t-ion-No. ~C-T/US8~/~07~5 can be performed separately, or, more conveniently, can be accomplished at the same time as reduction of technetium to an appropriate oxidation state.

~ cheme 6 lllustrates a method of part~cular use when the 11nkage between the carrier and chelate port10ns 1 s throush an -HH- funct10n which 1s part of an am1de or 1~1te or a very low pKa pr1mary or secsndAry ~mine. Conversfon of 2n ester group to the correspond~n~ a~de is accomplished with excess ~mmonlum. Then the chelat~ng agent precursor 4.
hav~ng a -COHH2 funtional group is subjected to H-hydroxyalkylat~on, e.g. by reaction with an aldehyde [e.g. formaldehyde~ benzaldehyde, acetaldehyde or chloral(Cl3CCHO)~; thus, for example, ~n the case of chloral, the CONH2 group becomes a ~13C-CHOH
CONH

function and thus forms a:suitable bridging group.
The resul~ant compound 1s then sub~ected to any method described herein or in the aforementioned PCT appli-cation ~or linking the carrier to an -OH function.
One such method, i.e. reacting the alcohol with nico-tinic acid in the presence of dicyclohexylcarbodiimide, is sho~ln in Scheme 6.
Sche0e 7 1s ~llustrat1ve .of a process 1n wh1ch the -NH- group to which the carr~er 1s to be l~nked ~s part of an ~m1de structure. The earliest steps of th~s Scheme are descr1bed in the aforementioned Fr1tzberg patent. Then~ 51 is reacted w~th excess ammon~a to for0 the corresponding succinamide which~
when heated. loses ammon1a to give the succ~nimide 52. That 1ntermedlate is then reacted w~th an aldehyde~
~s generally describeJ in the preceding paragraph, ~X67~

and the resulting -OH containing group then derivatized, also as described previously.
Scheme ~ i~?ustrates yet another alternate to Schemes 1 and ?; -~,4-diaminobenzoic acid is disclosed as a starting material for chelating agents in the Fri~zberg patent. Scheme 8 follows the reaction sequence of Scheme 2 and could be varied in any of the many ways described in con~unction with Scheme - 2 here~nabove~ Moreover, 5g could alternatively be subjected to the reactions shown in Schemes 5 and 6 and/or discussed in connection with those Schemes;
i.e. the -COOH group could be converted to a -CH20H
or a -CONH2 group and then derivatized as shown in and discussed with respect to those Schemes.
Schemes 9, 12 and 14 above illustrate typical conversion of a carboxylic ~cid ester group to the corresponding amide (-CONH2); reduction of the amide function to the corresponding amine (~CH2NH2); reaction of the -NH2 group with an activated ester of nicotinic ~ acid; quaternization with methyl iodide; and reduction of the resultan~ quaternary oP formula ~I) to the corresponding dihydro of formula (II), or convers;on of (I) directly to the formula (III) radiopharmaceutical~
These processes c~n be varied as discussed in conjunction with Schemes 3, 4 and 5 above.
Schemes 10 and 1~ above illustrate typical con-version of an alcohol (-CH20H~, which may be obtained from the corre~ponding carboxylic acid ester, to the corresponding nicotinoyl ester; reaction of the ester derivat~ve with methyl ~odide to afford the desired formula (I~ quaternary; and reduction to the corresponding formula ~II) dihydro or conversion directly to the corresponding ~ormula (III) radiopharmaceut~cal. For process var~ations~ see the d~scussion of Schemes 3, 4 and 5 hereinabove.
In Scheme 11 above, there is shown a ~ypical method for introducing a longer a7ky7ene chain between atom which is involved in forming the chelate structure and a pendan~ NH2 group which is to be coupled to the carr~cr moiety. As dep~cted in this scheme. a secondary amino group ,NH is reacted with a halo-alkamide, e.g. BrCH2CONH2, replacing the hydrogen of the ~ H with -CH2CONH2. Reduction of the amide affords the corresponding ,NCH2CH2NH2 compound. That amine can ~hen be reacted wi~h an ac~ivated ester of nicotinic acid, followed by quaternization and reduction as in ~he other schemes, For varia~i9ns, see in par~icular Schemes 3, 4 and 5 above.
Schemes 13 and 16 il7ustrate ye~ other ~ethods for lengthening the alkylene chain, the chain here being interrup~ed by one or more oxygen atoms. Thus, a -CH20H group ~s typically converted to the cor-responding 1ithium salt and then reacted with an iodo-alkanol, e.g. ICH2CH20H, to convert the -CH20-Li~ group to a -CH20CH2CH20~ group. rObviously9 the chain eould be lengthened by utilizing ~ longer-chain iodoalkanol, or by repeating the two steps just described ~in which case additi~na7 interYening oxygen atoms would be introduced.)} The -CH20CH2CH20H group is then converte~
to the corresponding nicotinic acid ester; which is 30 then quaternlzed to form the desired quaternary salt.
AgainO the reaction schemes can ~e varied as discussed with reference to Schemes 3, 4 and 5 hereinabove.

In Scheme 17 aboYe, reaction of an ~NH2 group with an ~ctivated ester o~ nicotinic acid, followed by quatern~zation, is shown. The resultant formula (I~ quaternary is then reduced as shown in the other schemes.
Many of the earliest steps in the reac~ion schemes depicted above paral~el reactions described in Fritz-berg U.S. Pa~ent No. 4,444~690. See, for exam~le, the conversion of ~ to 30 ~n Scheme 10; the conversion of 30 to 40 to 41 in Seheme 12; the conversion of 111 to 112 to 113 to 114 in Scheme 13; and so on.
_ Scheme 18 above, like Scheme 11 which has already been discussed, shows another typical method for intro-ducing a longer alkylene chain ~etween the nitrogen atoms. ~ere the secondary amino group `NH is converted to the corresponding ,NCH2CH2CH2NH2 group. The resultant amine can then be reacted with an actlvated ester of nicot~nic acid, followed by quaternization and reduction as in the other schemes. As a preferred alternative in this and many of the other reaction schemes depicted hereln, the quaternary chelating agent precursor of the lnvention can be prepared directly from react~on of the corresponding amine with a quaternized activated ester of nicotinic acid. Other 2~ variations will be apparent, e.g. from Schemes 3, 4 and 5 above.
Scheme 19 represents an alternate approach to the derivatives resulting from Scheme 1~ Obviously, this scheme could be varied ln a number o~ ways~ ~ost 3Q notably in the fourth step, where nicotinamide could be replaced with another am~de (e.g. one of those dis-~iEi7~
_gg_ cussed 1n Scheme 1) and where ICH2CH20H could bereplaced with another compound of the type I-ZI-OH
where Z' 1s Cl-C8 straight or branched alkylene.
Scheme 20 ~llustrates an alternate route to the derivatives of Scheme 8. This scheme represents a particular1y attractive synthetic route to the pro-tected quaternary derivative 62. Moreover, the intermediate 176 can be varied as discussed in con-j~nction with Scheme 19; also, this process can be adapted to the preparation of derivatives of other -COOH-conta~ning chelating agents, e.g. those of Schemes 1 and 2.
In Scheme 21, the intermediate 179, prepared as in Scheme 20, is used to prepare yet other compounds of the invention derived from 3,4-diaminobenzoic acid.
Scheme 22 is illustrative of yet another variation in the procedure of Scheme 8. Scheme 22 can be readily adapted to the preparation of other derivatives of this invention; see, for example, the discussions of Schemes 8 and 20 above.
In Scheme 23, there are depicted two hlghly desl-rable alternate routes to the quaternary salt 76 of Scheme 9. These alternate routes utilize the quater-nary activated esters of nicotin~c acid to prepare the quaternary derivative 7~6 directly from the correspond-ing primary amine 74. Use of either the succin~rnidyl or the phthalimidyl quaternary intermedia~es (17 or 191) ~s illustrated. Other quaternary activated esters for use in this reaction will be apparent from the various processes described hereln. After formation of the formula (1~ Quaternary such as 76, the process of Scheme 9 can then be used to prepare the other deriva~
tives of this invention.

Scheme 24 dep~cts yet another highly desirable alternate route to the quaternary salt 76 of Scheme

9. In this particular preferred scheme, a protecting group is introduced pr10r to introduction of the car-rier function; the protect~ng group is then removedprior to reduction of the quaternary function to the corresponding dihydro. In the case of the chelating agent shown in this scheme~ reaction with acetone protects both the secondary am1no ~nd thiol functions - lO by formation of thiazolidine structures so that those functions do not interfere during addit~on of the carrier moiety. Subsequently, the secondary amino and mercapto groups are regenerated by reacting the pro-tected intermediate with mercuric chloride in an organic solvent such as methanol, conveniently at room temperature, and then decomposing the resulting complex with hydrogen sulfide. See, for example, Rritish Patent Specification No. 585,250, which utilizes such a procedure for the production of esters of penicilla-mine. After preparing the ~uaternary salt 76 ir thismanner, the process of Scheme 9 can be used to prepare the other derivatives of thls invention. Yariations in the procedure used~ e.g. as discussed in connection w~th Scheme 23, can be used to obtain yet other deriv-atives of the invention Scheme 25 represents an alternate route to thecompounds obtained via Scheme 14. The route uses the preferred route of introducing the carrier ~o1ety in its quaternary ~orm and can be readily adapted to the preparation of derivatives of other -COOH containing chelating agents and/or introduction of other carrier moieties disclosed here-in.
.

ln Scheme ~6, there 1s ~llustrated a process for X

attaching a -C-R3-N ~ funct10n or analogous carrier molety to a pendant primary amine functlon in a chelating agent. This process ut~l~zes the ~hiazoli-dine structure to protect the secondary a~ino and thlolfunct~ons In the part~cular chelat~ng agent depicted9 as fully discussed in conjunct~on w~th Scheme 24 above.
An alternate approach to the derivatives depicted in Scheme 26 ~s shown in Scheme 27, in which the pri-mary amino group in the protected primary am~ne i5first converted to the corresponding -NHCO-R3-Br group~
which ~s then reacted with nicotinamide or the like to afford the protected quaternary Intermediate.
Scheme 27 depicts a process for preparing carrier-containing der~vatlves of yet another type of chelating agent. The desired chelating agen~ in this instance contains oxime functins, which are introduced after the quaternary form of the carr~er has been attached. For mation of derivatives of yet another type of chelating agent is deplc~ed in Scheme 29.
Slm~lar schemes can be shown for the preparation of the other der1v~tives o~ this invention. The steps of introducing and removing protecting groups are on7y included when necessary. Also9 the order of steps may be al~ered; in particular, quaternization may occur earlier in ~he reaction scheme, depending Of coUrse on the particu7ar compounds involved. Other react~on schemes, reactants, solYen~s, react;on con-~267~

d~t10ns, etc. w~lll be read~ly ~pparent to ~hose sk~lledin the art. A~so, insofar as concerns the quaternary derivatives~ when an anion differen~ from that obtained is des;red, the anion ~n the quaternary salt may be subjected to anion exchange via an anion exchange res~n or, more conveniently, ~y use of the me~hod of Kaminskj et al, Tetrahedron, Vol. 34, pp. 2857-2859 (19781. According to the Kaminski et al method, a me~hanolic solution of an ~X acid will reac~ with a quaternary ammonium halide ~o produce the ~ethyl halide and ~he corresponding qua~ernary ~X salt.
Reduction of the quaternary salt of formula (I) to the corresponding dihydro derivative of formula (II) can be conducted at a temper~ture ~rom ~bout -10C to room temperature~ for a period of time from about 10 ~inutes to 2 hour~, conveniently at atmospheric pressure. Typically, a large excess of reducing agent is employed~ e.g., a 1:5 molar ra~io of reducing agent to starting compound of formula (I). The pro-cess Is eonducted in the presence of a suitable reducingagent, preferably an alkali metal dithionite su~ch as sodium dithionite or an alkali metal borohydride such as sodium borohydride or lithium aluminum boro-hydride, in a sui~able solvent. Sodium dithionite reduction is conveniently carried out in an aqueous solutlon; t~e dihydro product of formula (II) is us~ally ~nsoluble in water and thus can be readily separated ~ro~ the reac~ion medium. In the case of sodium boro-hydride reduction, an organic reaction medium is employed, e.g., a lower alkanol such as methanol, an aqueous alkanol or other prot~c solYent. More typlcally, however~ the quaternary of for~ula (I) ls reduced in the same reaction ~xture as the reduction of tech-netium to an appropriate oxidation s~ate, affordqng the formula (III) radiopharmaceutical in one step from the formula (~) quaternary. Further details of the one-step reduction are given hereinbelow.
It will be apparent from the foregoing that a wide varie~y of derivatives of formulas ~I) through (IV~ can be obtained in accord with this invention.

10 In a partlcularly preferred embod1ment o~ th1s ~nvention, however, there are provided novel chelating agent precursors of the formula SH ~ ~
R5~C C~R6 ~'X-n ~la) R5 H~
9' wherein each R5 is independently selec~ed from the group consisting of H and Cl-C7 alkyl, or an R5 can be co~bined with the adjacent,C-R5 such that,C
R~
represents ~C~O; each ~6 is independently selected from the group consisting of H and Cl-C7 alkyl, or an R6 can be combined wi~h the adjacent ~C-R6 such ~R~
that,C \ represents,~=o~ HN ~ NH is a radical R~ Q
of the formula R7 ~7 ~7la~k)s-A~ ~ t~4] , 5alk)s-A!lOC~l where~n each R7 is independen~ly selected from the group consisting of H and Cl-C7 alkyl; (alk) is a straight ~r` branched lower alkylene group ~C1-C8) which additionally may contain l, 2 or 3 oxygen atoms in the chain, said oxygen atoms being nonadjacent to each other and also being nonadjacent to -A'-; X~ and n are as defined with formula (I); m' is a number which when multiplied by n is equal to one; s is zero or one; -A- is -NH-, -COO-, -O-, -CONH-, -N- wherein R8 is Cl-C7 alkyl, or -CON- wherein Rg is C1-C7 alkyl;
Rg when -A- is -N~-, -O- or 7 . then EQC~] is a radical ~8 of any one of formulas ~a) through (j) here;nabovei when -A- is -CONH- or -COy- or when HN NH has Rg ~ ..
15 the imide structure depicted above, then ~QC~J is a radical of any one of formulas (k) ~hrough ~s) herein-above; and when -A' is -~00-, then tQC+~ îs a radieal of any one of formula ~i) through (xiv) hereinabove.
Preferably the sal~ o~ ~ormula (laJ have ~he partial 20 structure ",SH HS H3C ~ ~SH HS~ ,~CK3 ~SH NS
oH2~ C~ H3C ~2C ~2~H3 o r H2C~ ~CH2 HN~NH

or are pos~tion isomers andtor homologs of the first two part~al structures shown. It is also preferred that when H
~ R~ ~ R~qlk~
then each R7 is preferably H and (a7k) is preferably a Cl-C6 alky7ene group, or a C~-C6 alkylene group interrupted by an oxygen atom in the chain; and that when ~ , HN ~ H~H

~alk)s-A-lQC~I -then (alk) is preferably a C1-C~ alkylene group, or a Cl-C6 alkylene group interrupted by an oxygen atom in the chain. When HN ~ NH is either of the above, ~hen the presently pr~ferred va1ues for -(alk)s -A-are -COO-, -CH20-, -CONH-, -CH2NH- and -CH20C~2CH20^, Preferred values for rQC~,7 in formula (Ia) are as given in conjunction with formula (I) hereinabove.
Corresponding to the preferred novel chelating agent precursors of formu7a (Ia~ are the preferred novel chelating agents of the formuld R5~ SH HS R~;

R5--C ~'R6 R5 ~ \~NH R6 DH
where~in R5 and R6 are ~s defined with formula ~Ia) and HN~ is a radical of the ~ormu7a OH

~9 H HN NH ~R`~H ~H

R7 R~ R7 ~lk)s-A-lDHcl, , 7 ~olk)s-A- ~DHC1 lDllCl wherein R7, (alk), s and -A- are as defined with formula ~Ia); when -A- is -NH-, -~- or -N- wherein R8 is C1-C7 R~
alkyl, then [DHC] is a radical of any one of formulas (a') through (j'' ) hereinabove; when -A'- is -CONH- or -CQr- wherein Rg is Cl-C7 alkyl or when Hh ~ NH
Rg DH
has the imide structure depïcted above, then ~DHC~
is a radical of any one of formulas (~'~ through ts'') - hereinabove; and when -A- is -COO-, then [DHC~ is a radical of any one of formulas (i') through ~xiv'') hereinabove. Preferred compounds of formula ~IIa) are the dihydro derivatives corresponding to the pre-ferred compounds of formula (Ia).
Likewise preferred are the novel radiopharmaceut;cals in which a formula (IIa) compound is chelated with a radioactive metal 9 especially with technetium. Es-pecial1y preferred radiopharmaceuticals have ~he formula Il R5~

wherein R~ and R6 are as defined with formula (la) and Njt_,N is a radical of the formula DH

~7~H N N N~
P~7 R~ R~ l ot k ) s -A - l D~ / q (~1 k)s-A- ID~C I f D~Cl wherein R7, alk, s an~ -A- are as defined with formula (Ia) and ~DHC~ is as defined with formula (~Ia) above;
and the corresponding quaternaries, "locked in" the brain, especially those of technetium, which have the formula ;5 ~R6 în~X~n tlVo) wherein R5, R6, m', X~ and n are as defined with formula (la) and N~N is a radical of the formula Q

R~ R~ R~ ~qlk)s-A
(alk)s-A- lOC~I lcic~]

wherein R7, alk, s, -At and tQC ~ are as defined with formula (la) above. The preferred complexes of formulas (lIIa) and (IVa) are those which cor-respond to the preferred derivatives of for~ulas (Ia) and (IIa3.

- ~ o~ -Chelating ~gent precursors, chelat~ng agents and r~dlopharmaceut1cals wi~h~n the purview of the presen~
invent10n t~n also be prepared by reacting ~ ~xs. H2N-CH2-CH2NH2 ~ NH-CH2CH2-~lH2 I ~ r ~ethanol or ,J ~methanol l I-I ~ H3 Ctl3 ~, and therea~ter reacting the amtno group of the - 5 ob~a~ned c~mpound 2~ wi~h the carboxyl group of compounds such as ~he 2 ~xoproplonaldehyde bis (th10sem1carbazone~ derivatives having a ~ree carboxyl group. ~llustrative of such compounds is 3-carboxy-2-oxopr~pionaldehyde bîs(N-methylthiosemi-carbazone~, a b1funct~onal chelat1ng agent described in Yokoy~ma ~t ~l U.S. Patent ~o. 4~2~7,36~.
The Yokoyama et al COOH- containing chelating agents also can be derivatized as generally described here-inabove for derivatizing COOH groups, e.g. as depicted in Schemes I and 2. Moreover, Yokoyama et al's chelating agents of the formula HooC-C-C-N-NH-~-NH-R4 R2 l R3-C=N-NH-C-NH-R4 ~6~8~
- 1 o 9 ~

wherein R1, R2, R3 and R4 are each H or C1-C3 alkyl can be first converted ko the corresponding esters ~e.g. replac1ng -COOH w~th -COOC2H5), which can then be reduced ~o the corresponding alcohols (replacing COOC2H5 with -CH20H) ~r converted to the corresponding amides; the alcohols or amides can then be converted to the corresponding carrier-containing derivatives;
see, for example, the d~scussion of Schemes 9-16 above.
Other process variations wil 1 be apparent from the many reaction schemes depioted hereinabove.
Another bifunctional chelating agent which can be readily converted to the redox system-containing chelating agent precursors, chelating agents and radio-pharmaceuticals of ~his invention is a compound of the formula CH3 /NH-C~HHCH3 / C~N S
NH2-CH~C
~ C N~ S
c~3 HH-~-NHCH3 which is also known as amino DTS and which is ~e-scribed in the literature, e.g. in Jap. J. Nucl. Med.
19, 610 (1982). Amino DTS can be readily converted to the derivatives of the present invention ~y reacting it with an activated ester of nicotinic acid or the like and quaternizing ~he resul~ing ester to afford the corresponding precursor of formula (I3, wh~ch can then be ut~lized as generally described herein to prepare the correspond~ng compound o~ ~ormula (Il~
and radiopharmaceuticals vf formulas ~III) and ~IV).
See, for example, Scheme ~0 below.

Yet another group of known chelating agents which ~s particularly well-suited for conversion to the redox system-contalning chelat~ng agent precursors, chelatlng agents and radiopharmaceuticals of the present inven-tion can be represented by the formula R ~N-(CH2)n~C=N--NH-C-~IHR

wherein Rl, R2, R3 and R4 are each H or Cl-C3 alkyl and n' is an integer of O to 3. See, for example, Yokoyama et al U.S. Patent No. 4,511,550 and Australian Patent No. 533.722. An especially preferred chelating agent encompassed by this group is known as amino-PTS, or AEPM, and has the structure H2H-C112CH2 4~3 C=H--NH-~-NHCH3 C=N--HH-C-HHCH3 Amino-PTS can be con~erted to the derivatives of the present ~nvention via the activated ester~ as described supra in connection with amino DTS. See, for example~
Scheme 33 below. The exact structure of the resultant technet~um complex 224 has not been determ~ned; it is poss~b1e that the C=N and C=S bonds are also reduced during one of the reductlon steps. One possible structure for 224 is as follows:

H3C ~3CONH-CH2CH2 ~3 ~HH-cH-NHcH3 CM--N~ S
tH3 HH-CH-HHCH3 (A similar structure could be depicted for complex 165 of Scheme 30).
A preferred alternate route to derivatives of am~no-PTS9 amino-DTS and the l~ke ls illustrated by Schemes 31 and 32 below. This route reacts a qua~er-nized activated ester with the ligand containlng a primary amine group to form the quaternary chelating agent precursor of formula (I) in one step. Var~ations in thls highly desirable single step, as well as in the two step alternative shown in Schemes 30 and 33, will be apparent from the discussion of a number of reaction schemes depicted hereinabove. Also, it should be po~nted out that introduction of the carrier moiety ln its quaternary form, typically via a quaternized activated ester such as 191 or lJ, is generally : advantageous over tlle two step method, and any of Schemes 6-7 and 9-17 hereinabove could be readily modified accordingly.

~2~39~

CH3 ~HH~-HHCH3 CH3~-NHCH3 ~ ~ ~5 ~, COOI~ NH -CH~C
HrC 1~ ~ ~CDIt~
,C~N ~H3 NH-~-NHCH3 CH3 NH~-NHCH3 16 S

161 ¦, CH31 ionlno DTS, o llsond ~escrlbe~, ~ex~le, H3C~ ~NH-C-NHCH3 ~, 610 ~1982)1 I H3C~N o ~C~N
~NH-CH~C~

~13CNH-~-HHCH3 /~c/-99~ ~ertechnetote reductta~, e.g.
/~d reduc ng osent, e,g. ~Ith H2524' /Ha2524~ In ~slc ~edllm In baslc ~edlua C lex o~ g~rco reduced ~or~
ot redox ~Ystem ~H3 /NH-C-HHCH3 165 H3C~ S
H~TcO4/reduc lng ~ Q
I ln YIYO c osent ~CNH-CH~\
J~co~ldotlon ~C~N
1~ CH3HH-C-NHCH3 awternory torm o~ rodloPhannoceutlcal ~locked In~ broln ~7~9 - 1 1 3 ~

Z ., Z Z ~

L,~ O ' ~Z-5 \0 ~ ~ \

^1 ~1 ~Z_~

T ~J

~ U
/ \ / \ ~1 0 '~ Z ~ o Z ~_~
z z ~ Cl ~ 2 Z \ ~\
O -- \
~Z-Y

C \
C
O
O ~

V

y n o c N
~=~ , _~ X ~ ~ X V~
~ o _, E 'Cl 2 C O _ ~ _ T ~, 1~ ~ O

~ .

Z
Z
Z
Z ~
Z
~T

I
2 \ ~I

T
~ ~ O

SQ~
~J 5~1 ~Z

~ T

T ~_) Z I O
O
T
.

ln a like manner, the presently contemplated car-rier system can be incorporated into the structure o~ a novel technet~um-99m radiopharmaceu~cal whose chelate portion is the residue of an amlno- or hydroxy-substi-tuted iminodiacetic acid, e.g., N-~3~ naphthyloxy)2-hydroxypropyl] iminodiacetic acld. Such substituted lminodiacet1c acid chelat~ng agents are known and are described in Loberg e~ al U.S. Patent No. 4,017,596;
such chelating agents can be protected to the extent necessary and then the trigonellinate or other carrier structure lntroduced through reaction with the -NH2 or -OH group in the chelating agent.
Similarly, suitable chelating agents and their precursors that include a d~hydropyridine-= pyridinium salt carrier system can be prepared by reacting Com-pound 17 or the like with a chelating agent which is a substituted-alkyl monophosphonic acid such as amino-butylphosphonic acid, 1,5-diaminopentylphosphonic acid, and the like. Chelating agents of this general type are also known and are illustrated by those descr~bed ln Kohler et al U.SO Patent No. 3,976,762.
Yet other chelat~ng age,nts containing one or two carboxyl functions are described in Fr~tzberg U.S. Patent No. 4,444,690. Carrler-containing technet~um chelates corresponding to the Fr~tzberg chelates can be prepared as generally described hereinabove and as illustrated g~

by Schemes l and 2 above.
Frltzberg U.S. Patent No. 4,444,690 describes an ~nteresting serles of 2,3-b~s(mercaptoalkanoam~de)-alkano~c ac~d chelat1ng agents of the general formula R R' HS-IH-CO-NH-e-X
HS -CH-CO-NH-C-COOH
R R' .

where1n X ~s H or -COOH, and R and R' are H or lower ~lkyl~ ~nd water-soluble salts thereofs used to pre-pare the corresponding radiopharmaceuticals of the ~ormula 8 /Tc~

R ~N N ~R
X R ~ R ~ C02H
where1n X 1s H or -COOH, ~nd R and R' are H cr lower a~kyl~ The Fritzberg chelat~ng agents are prepared from the correspond~ng 2,3-d~am~noalkano~c acids by ester~f1c~t1cn w1th a lower alkanol containing dry HCl, followed by treating the resultant alkyl ester w1th a chloroalkanoyl chlor1de to form the bis~chloro-alkanoa~1de)ester~ followed by treating that ester w1th ~ CSHa, followed by alkaline hydrolysis of the resultant 2,3-bis(benzoylmercaptoalkanoamido~-alkano1c ac~d ester to produce the 2~3-b~s(mercapto-alkanoam1do3alkano~c ~cld chelating agent. Preparation 78~9 -llB-of an ~nalog ~rom 3,4~d~am~nobenzo1c acld 1s also d1sclosed by Fr~berg. Many of Fritzb~ry3s synthet1c steps can be adapted to produce the formula (13 der~vat~ves o~ thls 1nvent~on 1n wh~ch, ln place of the ~COOH
~roup. ~n ~r~tzberg's chelatlng agent9 there ls an ~lk)s-A-~QC 3 group wherein the structura1 variables are as defined with formu7a (Ia) hereinabove. See, for example. Schemes 12, 13 and 16 above.
RAd1opharmaoeu~cals contain~ng a d~hydro-pyr1d~ne~_ pyrid~n~um s~lt carr~er system can also be prepared using a novel chelating a~ent precursor obtained by react~ng, in pyridine as the solvent.
tfie aforementioned Compound 29 with nitrilotr~acetic ~nhydr~de accord7ng to the known ~eneral procedure 111ustrate~ 1n Nunn et ~l U.S. Patent No. 4~4l8,~08.
The d1cdrboxyl pyr1d1nfum salt obtafned ~rom the above reaction is obta~ned ~n puri~ed form as fol10ws: The volat~le components of the reaction mfxture are evaporated to an olly semisol~d on a ro~ary evaporator~ A so~ut1on of 10 peroen~ aqueous sod~u~ hydroxide (w/v) ~s used to dissotve the olly sem~solfd. The result~n~ so7utlon is extracted w~th ~ethy7ene chlor~de to remove the remaining pyridine from the aqueous phase. ~he pH va7ue of the aqueous phase ~s therea~ter low~red to a value of abou~ 6-~.
~he resultfng aqueous solution ~s then reduced in volume to about that of She origina1 pyrld~ne so1ution, and abou~ ~ve ~mes that Yolume olF a satura~ed so~ution of picric acid is added to for~ d picr~te deriYative 30 precip~tate.

The picrate precip~tate ~s washed w1th cold, dist111ed wat~r~ and ~s then dissolved in a 10 percent aqueous solution oF hydrochloric acid (v/v). The resultiflg solut~on ~s extra~ted with methyl chloride unt~l there Is no more ye~low color ~n the aqueous or methylene chlorlde phases. The resultin~, colorless aqueous phase ~s concentrated to ~bout the volume of the or~glnal pyrid~ne solution, and is then lyophylized ~o prov~de the chelatinQ agent in dry form.
The dr~ed chelating ag~nt is ~hen dissolved in ethanol and precipitated us~ng the diethyl ether flooding technlque described in Example 4 hereinbelow.
Still another usef.ul chelating agent precursor can be prepared by react~ng equimolar quantities Qf lS ethylenediaminetetracet~c acid and acetic anhydrjde 1n dry pyrldine follow~ng the teachings of Nunn et al U.S. Patent No. 4,418,208, dnd thereafter reacting J further equ~molar amount of ~ompound (29) to fnr~
the monoamide adduc~. ~he tridentate chelating agen~
sa1t is obtained as deseribed immedia~ely above.
The tr~dentate chelating ~gent precursor salt so obta~ned ~5 thereaf~er reacted with the 9gm per-technate ion as described In Example 5 below, which reduces both the technetium and the pyridinium salt, to for~ a 1:1 ligand:radioactive metal ion complex drug delivery system of this inYention. The complex so formed is ionically neutral inasmuch as ~he five valences o~ the reduced technetium-99m metal are taken up with one oxygen atom and three carboxylate oxygens~ and the pyridinium ring is in its reduced, dihydropyridine form.

~Lz~s~
-l20-As a~oresa1d, the preparation of the chelating agent precursors, chelatlng agents and radiopharma-ceut1cals of thls inventlon must be tailored to the part~cular starting materials used, espec~ally as S regards the presence of reactive functiondl groups in ~dd1t~on to ~he group whirh is to be l~nked to She carrler molety. The sta~e at which the o~rrier is introduced and ~he ~anner in which the carrier is - ~ntroduced w~ll be determined according1y. Often IO the carrier must be introduced in quaternary form at an early stage of the synthesis as illustrated here-~nabove. When not so requ~red, it may be more de~irable to react an appropriate ~tarting material such as nicotini~ anhydride w~th an NH2- or OH- containing ll~and or ligand precursor~ and quaternize at a later stage, after coupling the ligand ~chelating agent) ~nd the 3-pyr1d1necarbonyl group.
The processes depic~ed ahove are only intended to be illustrative. Many variations, for example.
can be made in the chelatin~g por~isns of the molecule, and suoh varia~icns wil1 naturally affect ~he synthetic scheme, particularly as regards the necessity for introducing protecting groups and subsequent removal thereo~.
In order to further illus~rate the prPsent inventisn and the advan~ages thereof, ~he following specific examiles are given, it being understood that same are intended only as illustrative and in no wise limitatiYe.

Example 1: ~ (t-butoxycarbonyl),N-(2-mercaptoethyl)-glycyl N'-(2 aminoethyl~homQcysteinamide (Compound 14 ~f Scheme 3~

N-(t-butoxycarbonyl),N (2-mercaptoethyl)glycyl homocysteine ~hiolactone (13) is prepared as described ~n xamples 1 and 2 o~ Byrne et a7 U.S. Patent No.
4,434,151, and is dissolved (1.0 gram; 3 millimoles) in 25 milliliters of tetrahydro~uran ~THF~. The result-ing so~ution is then coo~ed to about 0C., and ethyl-enediamine (1.8 grams; 30 millimoles) is added toform a new solution. The resulting new solution is main~ained for about one ~aur. The Yolatile components of the solution are ~hereafter remoYed with a rotary evaporator. n-ButanOl (about 10 milliliters) is added to the ~dr~edll solut10n components an~ the llqu1d components of the resul~ing composition are again removed by rotary evaporation. The last step is repeated until the vapors remaining in the evaporation vessel do not cause a moistened pH-indicator paper to indicate a bas1c pH val~e~ thereby ~lso ~nd~cat1ng that the ethylenedla~1ne h~s been substanti~lly removed ~nd that the N- ~-bu~oxycarbonyl~,N~ mercapt~ethyl)-glycyl N'-(2-aminoe~hyl)homocysteinamide so obtained 1s substan~1~11y pure.

: Succinim~dyl nicotinate (Compound 16 of Scheme 3) ~ Icotln~c ac~d (12.3g~ 0.1 ~ole) and N-hydroxy-succ1n1~de (11.59; 0.1 mo~e) are dissolved ~n 300 ~ 1ters of ho~ d~oxane. The mlxture fs cooled on ar Ice-bath ~nd dlcyc70hexylcarbodi~mide t20.69;
0.1 ~ole) In 30 ~ 11ters o~ dioxane ~s added. The react~on ~xture fs st1rredD W~th cooling, for ap-prox~mately three hours, then refr~gerated for at le~s~ 2 hours. ~he prec~p~tated dicyclohexylurea ls removed by f~ltrat~on, ~he solution is condensed under ~acuum, and the ye~low~sh solids whlch precipitate are recrystall~zed ~rom ethyl acetate. White crystals (14g) of succinimidyl nicotinate are obtained (Yield 63.6X~. Str~cture of the product is confirmed by NJ~R o Example 2b Succinimidyl Trigonellinate (Co~pound 17 of Scheme 3~

Succinimidyl nico~ina~e 16 ~3.3 ~; 15 mmole~ is dis-solved 1n 50 ~111111ters of d~oxane and 3.7 mill~liters ~8.2g; S0 ~mole) of methyl 10d~de Is added. The react~on ~Ixture 1s refl~xed for ~bout 48 hours. The ~ellow crysS~ls wh~ch prec~p1tate dur~ng ~he react~on are re~oved ~y f1lSrat~on, washet w~th ethyl ether and dried under vacuum a~ 40C. Succinimidyl trigonellinate (5.2g) ~s obtained (Y1eld 96.3X). Structure of the product 1s sonf1r~ed by NMR.

An lmproved method ~or preparing Compound 17 is as follows A solution o~ 9.0 9 (41 mmol) of the ester 1~6 and

11.6 9 (82 mmol) of methyl iodide in 40 mL of anhydrous acetone is heated in a pressure bottle under an argon atmosphere for 16 hours. The yellow precipitate which forms is removed by filtration. Yield 14 9 of Compound 17, darkenlng at 170C and melting at 197~C.

Example 3: N-(_-butoxycarbonyl), N-(2-mercapto-ethyl)glycyl N'-~l-methyl-3-(2-N-ethyl)carbamoylpyridinium iodide]homo-cysteinamide (Compound 18 of Scheme 3) N~(t-butoxycarbonyl), N-(2~mercaptoethyl)glycyl N'-(2-arninoethyl)homocysteinamide --Compound 14~- (1012 grams; 0.003 mole) and succlnimidyl trigonellinate --Compound lJ-- (0.70 gram; 0.0025 mole) are d~ssolved in 25 milliliters of dry pyr~dine with st~rring. An ap-propriately sized, "micro" Dean-Stark trap and condens-er are added to the reaction flask and the solution isheated to and maintained at a temperature of 80C until substantially all of the succinimidyl ester is replac-ed. The pyridine is removed on a rotary evaporator using n-butanol as a "chaser" as described before for the ethylenediamine removal. Once the pyridine is re-moved, the drled re~ldue is triturated with THF and the solid is removed by filtration and washed several times with THF with care not to dry by air suction. The solid so obtained is thereafter dried in vacuo to provide Compound 18, N(t-butoxycarbonyl)~ N~(2-mer-captoethyl)glycyl N'-[l-methyl-3-(2-N-ethy~Jcarbamoyl-pyridinium iodide]homocysteinamide.

Example 4: N-(2-~ercapt~et~yl)glycyl M'-tl-methyl-3-(2-H-ethyl)-carbamoylpyridln~um lodide~
homocystelnamlde ~Compound 19 of ~cheme 3 ) N- ( t~ butoxyea rbonyl ? ~ N- t2-merca ptoethyl ~ ~lyoyl N' ~ Tuethyl-3- (2-N-ethyt ~carbamoyl pyridlnium lodide~
homocystelnamlde --Compound 18~-(1.24 grams; 0.002 mole) 1s d1ssolved w~h s~rrlng ~n absolute ethanol (50 m~lllllters) and eooled to about 0G ln an 1ce-water bath. HCl gas ~s bubbled hrough ~he stirred solu~lon for I5 m~nutes, and the so1utlon ls thereafter stirred for an add~tional I5 mlnutes. Diethyl ether (200 mil-1111ters) ls thereafter added ~o ~he solution to pre-clpitate the salt~ The preclpitate is filtered and washed with diethyl eSher wlth oare not to dry the prec1p~tate by air suc~lon. The solid 1s then dried ln vacuo to provlde N-(2-mercaptoethyl)glycyl-N'-~I^methyl-3-(2-N-ethyl )carbamoyl pyridini um ~o~ide~
homocystelnam~de.

Example 5: Complex Between N-(2-mercaptoethyl )glycyl-N'-[I-~ethyl-3-(N-2~ethyl)carbamoyl-I,4-d1hydropyrldyl~homocysteinamide and the Oxotechnate-99m ~on tCompound ~0 of Scheme 3) H~t2-mercaptoethyl)-ylycyl-N'-Ll-methyl-3-(2-N~ethyl~carbamoylpyridinium iodide]homocystein-~mlde --Co~pound 1~ 9 m~ grams; 0.17 m111~mole~
1s dissolved ln I.O mi11~1iter absolu~e ethanol and I.O mlllgllter of IN NaOH. A I.O ml~l111~er senerd~or eluant o~ 99mTs04 (5 ~o 50 milliCuries) ln s~line is added. Then, 0.5 mil~111ter o~ d~thionite solu~on, prepared by disso~v1ng 336 milligrams of Na2S20~ per m~ ter of 1.0 NaOH, ts added and the mixture heated suff~c1ently to reduce both ~he technet~um and the pyrldlnlum salt ~nd to form the complex between N-(2-~ere2ptoethyl)91ycyl-N'-~l-me~hyl-3-tN-ethyl3car-.5 amoy~-1,4_d~hydropyridylJhomocysteinamlde and the oxotechnate-99m ~on. ~he complex so prepared Is buffered by the ~ddition ~f 1.0 milliliter of lN HCl and ~.O ~illiliter of O.l ~o7ar NaH2PO4, pH 4.5 buffer.
Example 6: Complex 3etween N-(2-mercaptoethyl)glycyl-N'-[l-methyl-3-~N-2-ethyl)carbamoyl-1,4-d~hydroqu~nolyl]homocysteinamide and the Oxotechnate-99m ion A rad~opharmaceutlcal coupled to a carr~er based upon a reduced, dihydroquinoline carrier such as the title complex can be prepared following the steps out-l~ned in Examples 1~5" but replacing the nicotinic ac1d In Example 2a w~th an equ~valent quantl~y of 3-qu~nol1necarboxylic acid.

Example 7: N-[2-(acetamldonlethyl)mercaptopropionyl]-~O glycyl N'-(2-amlnoethyl)homocystelnamlde (Compound 2S of Scheme 4) N-~2-(S-acetam~domethyl)mercaptopropionyl)_ glycy1 homocysteine ~h~olac~one (Compound 24 of Scheme 4), prepared as described in Examples 7 and 9 of B~rne et al U.S. Patent No~ 4,434.151, ls suspended tloO gram; 3 millimoles) in 25 milliliters of THF.
The resultlng suspens10n 1s coo~ed to a temperature of abou~ 0C. 1n an ~ce-water bath, and ethyl-enedia~ne ~1.8 grams; 30 ~ 1moles) is added to for~ ~ new solu~on. N-[2-(acetamidomethyl) m~r-captoprop10nyl3gt~cy~ N'-(2-am1noethyl)homocystelnam1de 1s thereafter obta~ned 1n ~ manner substantlally s1~11ar to that descr~bed 1n Example 1 for the analogous co0pound .

Example 8: N-(2-taceta~o~ethy?~meroaptoprop~onyl3-glycyl N'-rl methyl-3-(2-N-ethy?)carbamoyl-pyridin~um ~odide]homocysteina~lde (Compound 26 of Scheme 4) Compound 26 of synthet~c Scheme 4 is obtained in a manner analogous to that used in Example 3 to prepare Compound 19, but Compounds 17 and 25 are ut~lzed as starting materfals.
5 Exa~ple 9: Comp~ex Between N-(2-mercaptoproplonyl)~
glycy?-H'~ ethyl-3-(2-H-ethyl~carbamoyl-1,4-d~hydropyrfd~ne3homocyste~ndmlde and the Oxotechnate-99m ~on--(Compound 27 of Scheme 4~

Compound 26 of Example 8 ~0.17 millimole) is d~ssolved in l.O m~llll1ter of abso?ute ethanol and 1.0 m111171ter of lN NaOH. The comp?ex of this Ex~mp~e 1s thereafter prepared ~n a m~nner ana~ogous to that described for the complex of Example 5, Here~
the bas1c sol~t10n frees the 2-mercaptopropionyl group from its protect~ve N-methylene ~cet~m1do group, whi1e ~he d1th10nlte reduces ~oth the pyr~din~um an~ ~echnetium sal~s.

æ~

Examp~e 10: 3,4-d1th~a-~,2~5,5-tetramethylhexane-1,6-d~one ~Compound 68 of Scheme 9) T~ ~ st1rred solut10n cont~ln1ng 115.6 9 (1.6 ~ol ) of Isobutyraldehyde 67 ln 184 g of carbon te~ra-chlor~de are added dropw~se, at flO-50C, 108 9 ~0.8 ~ol ) of 97X sulfur monochlor~deO The add~t lon is carr~ed out during ~ 2.5 hour period~ under a nitrogen atmosphere, w~th occas~onal cooling. The solution ~s ~a1nta~ned a~ 30-45C, w~th s~rr~ng9 for an ad-dit~onal 48 hour per~od, ~nder a current of nitrogen9 to remove ~he hydrogen ch~or~de liberated. The solution ~s dls~lled under v~cuum to g~ve 72 9 of the desired 3,4-d~th~a-2,~,5,5-tetramethylhexane-1,6-dione, i.e.
Co~pound 68 of Scheme 9. lH NMR(CDC13)~ 9.1(s,?-CH0), 15 1.4tS~12~-~(CH3)2-].

Example 11: Ethyl 2,3-(dlammon~um~propionate dichloride - (Compound 70 of Scheme 9) To 10 9 (0.07 mol) of ethyl cyanoglyoxylate-2-ox~me 69 are added 125 mL of absolute ethanol, 15 g of hydrogen chlor1de gas 2nd 1 g of platinum oxide~ The ~xture ls hydrogenated us~ng a P~rr-hydroqenation apparatus" Hydrogen uptake is complete i~l 3 houns.
rhe product fs removed by f~ltration and taken up ~5 ~n 75 mL of hot 95X ethano~. The ethanol solution ls fi ïtered. The filtra~2 is then cooled and the crystall~ne product wh~ch separates on standing ~s removed by f ~ l trati on . There ~ s thu s ob~a I ned ethy1 2, 3 -(d1ammon1um)prop~onate dichloride, i.e. Compound 70 of Scheme 9. Y1~1d 5 g ~35~), melting polnt 1~4-1~6C
(l~t. 164.5-165C); 1H NMR~D20) ~ 4.5(m,3,-NCHCG~, -OCH2CH3), 3.5(n1,29-NCH2CH-~, 1.3(t,3,-OCH2CH3).

Example 12: 5,8-d~aza-1,?-d~th~a-6-ethoxycarbonyl-3,3,10,10-tetr~methylcyclodeca-4,8-dlene.
tC~mPound 71 of Scheme 9 Procedure I

S To 1~0 9 (5 mmol) of the blsaldehy~e 68 is added dropw~se a solut~on of loO g (S mmol) of the ester 70 and 0.9 mL of pyr~dine ~n 30 mL of methanol at 0C
~htle under a nitro~en atmosphere. The add~tion takes pldce dur1ng a 10 m~nute per~od. The solution ~s then &llowed to stand for 1 hour, a~ter which time 10 mL of water ~s added. The solution turns ~urbid and warms to 26C. The solut~on is stirred for an add~tlonal 20 m~nute period, after w~ich t~me the wh1te preclp1tate ~h~ch forms set~les out of solution.
The preclp1tate ~s removed by filtration and then take~ up 1n chloroform. The chloroform solut~on is dr1ed over sod~um sulfate. RemoYal of the solvent and tr~turat~on of ~he residue with petroleum ether g~ves wh~te plate-l~ke crystals of the des~red product, ZO 5,8-dlaza-1,2~d1thia~6-ethoxycarbonyl-3,3,10,10-tetra-methylcyclodeca-4,8-dfene, ~.e. Compound 71 of Scheme 9, ln 53X y1eld (1 9~, melting point 98-99C. IR (thin f1lm) 3450D 1740, 1650 cm~1; 1H NMR(CDCl3j ~ 6.9(m,Z,C-H-CH-~, 3~-4.6g~,5~-OCHzCH3, -NCH2CH-N-)~ 1.5~m,15,2~C~CH3~2, -OCH2~H3~ "

Procedure I I

To 1.0 q (5 mmo~ j of 'che bisaldehyde 68 in 10 mL
of tnethanol ~s ~dded dropwise 1 .Q g (5 mmol ~ of the ester 70 and 1 9 (12 mmol ) of sodium bicarbonate in 20 mL of a 50:50 by volume m~xture of methanol and water. The al~xture ls st~rred at 0C for 10 m~ nutes, after whlch ~1me 10 mL of wa~er ~s ~dded. The re-sult~nt m~xture ~s maintained at room temper~ture, wlth st1rr~ng~ for 2 hours. ~later is added ~nt~l S the wh~te prec~p~tate wh~ch forms separates out of solut~on. The precip~tate ~s removed by fil tration ~nt ~aken up ~n chlorofor~. Removal of ~he sr,lvent by rotary evaporation affords 0.4 9 (21X yield) of Compound 71, having a melting point and 1H NMR spectrum lO ident~cal to the product of Procedure I.
Procedure III

A solution of 8 g of the ester 70 and 7 mL of pyridine in 200 mL of methanol is added dropwise over a two hour period to a solution of 8 g of bisaldehyde 68 in 25 mL of methanol. The reaction mixture is cooled in an ice bath after the addition for 1 hour, then is allowed to remain at room temperature for 1 hour. The reaction mixture is then placed in a freezer (-20C) overnight. The solution is concentrated to one-third volume, water is added and the aqueous solution ~s extracted with chloroform. The chloroform extract i5 washed w~th saturated aqueous sodium chlor~de solution and dr~ed over magnesium sulfate. Removal of the solvent leaves a viscous mass, which is dissolved in 20 mL of hexane. The hexane solution is cooled in an acetone/dry ice bath until a white powder separates.
The product is removed by filtration and taken up in chloroform. The chloroform solut~on ~s concentrated.
White crystals of Compound 7~1 are formed on stardlng~
Yield 7 9, meltiny point 95-96C. NMR and IR as ~n Procedure 1, -13~-Example 13: 6-carbamoyl~5,8 ~za-1,2-d1th1~-3,3,10,10-tetramethy~cyclodeca-4 ~8-diene (Compound 72 of Scheme 9 Procedure l:
.
A so~t~on of 5 9 of the ester 71 ~n 20 mL of tetrahydrofuran and 20 mL of aqueous ammonia ~s stirred at room temperature for 2 hours~ after wh~ch time ~t ~s a71owed to s~and ~t room temperature for 24 hours. Re~oval of so7ven~ leaves a white powder wh~ch ~s removed by fil~cra~on. llhe product, 6-carbamoy7-SD8-dfaza~1,2-d~th~-3,3,10~10-tetramethy~cyclodeca-4,8-d~enec ~.e. Compound 72 of Scheme 9, is crysta11ized from a m~xture of ~sopropanol and water. Yield 4 9 ~88~ el~nq point 181-183C. IR (KBr) 3300" 3100, 1650 cm -1; 1~ HMR(CDC13) ~ 7~0(~,2~-HC=N-), 6.4(broad bandl,2, -CONH2~, 3,8-4.6rm,3, -NCH2-CH(N-~CO-~, 1.5 1 ~4[s ,12 ,~C (CH3 )2~

Procedure 11 _ _ A solution of 5 9 of the ester 71 ~n 20 mL of tetrahydrofuran, 20 mL of ethanol and 20 mL of aqueous ammonia (28g) is st~rred at room temperature for 16 hours. Removal of the solvent leaves Compound -7? as a white powder, which crystallizes from toluene as white plates. Y~eld 4 9~ meltlng point 193-1g4~. IR and NMR as in Procedure I.

~`~

Example 14: 5-carbamoyl-5,B-d1aza-1.2-dlthl~-3,3.10,10 tetramethyl cyclodeeare (Compound 73 of Scheme 9) To 3.7 g of ~he am~de 72 in 25 mL of 95~ ethanol 1s added 2 g of sod1um borohydr~de. The mixture is st~rred at room temperature for 2 hours, then ~s heated at reflux for 2 hours. The solution is thereafter concentrated ~n vaeuo ~nd water is added to precipitate the product. The white crystalline produc~ is removed by f~ltration. Recrystallization from a mixture of ~sopropanol and wa~er affords 6-carbamoyl-5,8-diaza-1,2-dithl~-3~3,10,10-tetramethylcyclodecane, i.e.
Compound 73 of Scheme 9t as fine white needles melting at 138-139C. Yield 3 9. lH NMR(CDCL3) ~ 2.3-4.0tm,7, -HCH2CH-H-, 2-HCH2-C(CH3)-S-~. 1-8(broad b~nd9 2 -CONH2)~ 1.3rm~14, C(CH3)2, -CNH-CHz-]~

Exam~ 5-aminome~hyl-4,7-dia~a-2,9-dimethyldecane 2,9-dith~ol (Compound 74 of Scheme 9) A solution of 1.8 g of the amide 73 in 50 mL of dry te~rahydrofuran ~s added dropwise to a slurry of 1 9 of l~thium alum~num hydride in 100 mL of dry ~etrahydrofuran. The addit~on takes place over a 30 m~nute per~od. The ~ix~ure is then heated at ~he reflux temperature for 20 hours. At the end of that tlme, the reaction m~xture ~s firs~ cooled and then quenched w1th saturated Na-K ~artrate so7u~ion. The aqueous phase 1s extracted with chloroform. The com-b~ned organic phase ~s then dried over sodiu~ sulfate.Removal of the solvent by rotary evaporation affords, as a v~seous oil, 5-aminomethyl-4 ,7-d~aza-2,9 dimethYl-decane-2,g-d~t~io7, ~,e. Compound 74 of Scheme g~ lH NM~
~CDC13) c 2.8~m,9,-NCH2~H-C(CH2)NH-. 2-NCH2-C(CH3)~S-~, 1.5~m,14,~C~CH3)2~ -SH]-Example 16: 5,8-d~aza-1,2-d~thla-3,3910~10-tetra~
~ethy7cyclodeca-4,8-d~ene (Compound 87 of Scheme 11) To 3.15 9 of the d~a~dehyde 68 is added 4~0 9 of ethylened~amine, w~h stirr~ng and cooling~ oYer a per~od of 10 ~fnutes. The thlck m~ss wh~ch results ~s st1rred ~or an add~t~ona1 one minute period, then a11Owed to stand for I hour ~t room temperature and s~bsequently cooled for lS hours in a freezer (-20C).
The solld is removed by filtration and washed with 500 mL of wa~er. The white product is then taken up in chloroform and the chloroform so~u~ion is dried over sod~um sulfate~ Removal of the ch~oroform gives 2.5 9 of 5,8-dia2a-1,2-dithia-3,3,10,10-tetra-~ethylcyclodeca-4,8-dlene, ~.e~ Compound 87 of Scheme Il, as a white crysta11ine produc~, me1ting at 168-170~C (1~t. 162~164C, 163-166C). lH NMR(C~C13~
~ 6.9(s,2,-HC=N-)~ 4.2,3.0(doublet of doub7et, 2, 2-C~ -C~23~ 1.40~sD6,-C(CH3)2~]. Anal. Calcd. for C10 C18N2Sz: C, 52.13; H, 7.88; N, 12.15; S, 27.83.
Found: C~ 5Z.20; H, 7.909 N, 12.14; S-~ 27.74.

~: 5~8-d~aza-1~2-dithia-3,3~10,10-tetra-methylcyc~odecane (Compound 88 of Scheme 11) A solu~on of 0.5 g of 87 and 0.3 ~ of sodium borohydride in 23 mL of ethanol ~s st~rred at room temperature for 1 hour, then Is heated at ~he ref~ux temperature for 20 m~nutes. Then~ 10 mL o~ water are added snd the m1xture is hea~ed for an addi~iona7 10 ~inutes.
30 The solvent ~s partt~ly removed by rotary evapor~tlon and the res1due ~s extracted three times with 10 mL
port~ons o~ chlorofcrm. The chloroform extr~ct ~s dr1ed o~er sod1um sulfate and the solvent 1s removed by rotary eYaporatlon. The resultant liqu~d so~ld~fies on coollng. Flash chromatography (eluent hexanes~di-ch~orome~haneffsopropanol 5:1:1 by volume) gives 5,8-d1aza-1D2-dfthla-3,3,10,10_tetr~methy1Oyclodecane, 1.e. Compound 88 of Scheme 11. as a solid. melting at 52 53C. lH NMR(CDC13) ~ 3-2.1~m,10 r~ng protons), 1.1~1-2(5~6 Cff3. CH3)-Exampl e 18: N-t(4 ,7-diaza-2 ,9-dimercapto-2,9-dimethyldec-.
5-yl)methyl~niootinamide (Compound 75 of Scheme 9~

A solution of 9 mmol of the activated ester 16 in 30 mL of dimethoxyethane is added dropwise over a period of one hour to B.4 mmol of ~he amine 74 in 70 mL o~ dimethoxyethane. Thin layer chromatog;aphy after one ho~r~ using a so~vent system of petroleum ether/acetone/dichloromethane/isopropyl alcohol (10:5:5:1 by volume)~ ~nd~ca~es a major component has been obta~ned. The solvent ~s removed by evap-oration and the residue is trea~ed with water. The resultant mixture ~s extraoted with ohlorGform and dried over sodium sulfate. RemoYal of the solvent affords the des~red product, Compound 75 of Scheme 9.

Ex~ple 19~ 3-~N~ ',7'-diaza-2',9'-dimercapto~
2',9'-dimethyldec-5'-yl)methyl~carbamoyl~-1-methylpyr~dinium iodide (Compound 76 of Scheme 9) Compound 75 is reacted w~th methyl ~odide according to the general procedure described in Example 2b above.
Prepared in ~his manner is the desired quaternary salt, ~.e~ Compound 76 of Scheme ~.

Example 20: Complex forma~ion The general procedure of Example 5 can be repeated to convert the other quaternary salts of formula (I) - to the correspanding radiopharmaceu~icals, e.g. to convert Compound 76 to Complex 78, Compownd 83 to Complex 85 and so forth.

Examl~le 21: 5-am~nomethyl~4,7-d~aza-2,s-dimethyl-decane-2,9-dith~ol (Compound 74 of Soheme 9) rO a slurry of 11 9 of lithiurn aluminum hydr~de ~n 300 mL of dry tetrahydrofuran ~s added dropwlse, over d 2 hour period and under an argon atmosphere, 13 9 nf the amide 72 in 150 mL of dry tetrahydrofuran. After the addition is complete, the reaction m~xture is heat-ed at reflux for 30 hours, then quenched with satur-ated Na-K tartrate solution. Treatment with 3N hydro-chloric acid and then with saturated sodium carbonate solution~ followed by filtration and extraction of the filtrate with dichloromethane, affords an organ~c solu-tion which is dried over magnesium sulfate. Removal of the solvent affords the desired amine, Compound 74 of Scheme 9, as a viscous oil.
A sample of the free amine thus obtained is dis-solved in dlethyl ether and hydrogen chloride gas is added. The white powder which separates is removed by filtration and purified from ethanol/water to give the corresponding hydrochloride salt melting at 225-228~C.
H NMR (D20) ~ 3.3-4.2(m,9H,HCl,NH2CH2, -HCl NHC~ ), 1.5~m,12H,C(CH~)2]. Anal. Calcd. for C11H30C13N3S2 H20: C,33.63; H98.21; N,10.69; Cl,27.07; S,16.32.
Found: C,33.93; H,7.94; N,10.60; Cl,27.05, S,16~25.

Example 22: Comound 192 of Scheme 24 A mixture of 1 9 of the amine 74, 75 mL of acetone and a catalytic amount of p-toluenesulfonic acid is heated at reflux for 24 hours. The solvent is removed by rotary evaporation and the residue ls taken up in chloroform and treated success~vely with saturated aqueous sodium bicarbonate solution, aqueous sodium ~ 2 hydrox~de solution (10~) and saturated aqueous sodium chloride solution. The solution is dried over magnes-ium sulfate. Removal of the solvent leaves a viscous mass. Thin layer chromatography (CHCl3/methanol, 2:1) ~ndicates two major components having R~ values of 0.13 and C.73. The component with the lower Rf value shows a positive ninhydrin test, confirming that it is the desired primary amine 192, while the component with the higher R~ v31 ue is negative. IH ~M~ of the Rf 0~73 10component (CDCl3): ~ 2.9, 2.5, 1.3-1.5. lH NMR of the Rf 0.13 component (CDCl3): ~ 3.0, 2.8, 2.3, 1.2-1.7.
Obtained in this manner is the desired bisthiazolidine primary amine, Compound 192 of Scheme 24.

Example 23: Compounds 193 and 76 of Scheme 24 15Reaction of the bisthiazolidine primary amine 192 with the quaternized activated ester 17 or 191 affords the corresponding bisthiazolidine quaternary, ~.e. Com-pound 193 of Scheme 24, which can then be de-protected, e.g. by reaction with mercuric chloride, followed by treatment with hydrogen sulfide, to give the unpro-tected quaternary, Compound 76 of Scheme 24.

Compound 81 of Scheme lO

A solution of 7 9 (3 mmol) of the ester 71 ~n 50 mL of dry tetrahydrofuran ~s added dropw~se over a per10d of 1 hour to 1.8 9 ~47 mmol) of lithtum aluminum hydride in 200 mL of dry tetrahydrofuran. The mixture is heated at reflux for 16 hours, after which time the reaction is quenched w~th K-Na tartrate solutlon. The organic phase is dried over sodium sulfate. Removal of the solvent leaves a yellow viscous mass. Yield 4 9 (65%) of the desired alcohol, Compound 81 of Scheme 10. lH NMR (CDC13) ~ 2.2-Z.8, 3.5, 2.3, 1.5.

Example 25: Compound 83 of Scheme lO
-Following the general procedure of Example 22, but subst~tuting an equivalent quant~ty of the alcohol 81 ln place of the amine 74, affords the bisth~azolidine alcohol, i.e. the protected counterpart of Compound 81 of Scheme 10. That protected alcohol can ther, be sub-jected to the procedures detailed in Example 23 above to ultlmately give the corresponding unprotected qua-ternary, Compound 83 of Scheme 10.

~ 7 Example 26: Compound 32 of Scheme 5 A solution of 17 mL of 2N llthium borohydr~de in tetrahydrDfuran is added to 300 mL of dry tetrahydro-furan under an argon atmosphere. To that solution are added 10 g (0.035 mol) of the ester 40 in 100 mL of dry tetrahydrofuran. The resultant cloudy solution ls heated at reflux for 105 hours. The reaction is quenched wi~h water and the organ~c phase ~s washed with saturated aqueous sodium chlor1de solution and dried over magnesium sulfate. Removal of the solvent leaves, as a ~hite powder which is very soluble in water, the corresponding primary alcohol, Compound 32 of Scheme 5. Yield 2 g (24X); melting point 85 90C;
lH NMR (acetone-d6) ~ 7-8, 4.15, 3.3-4Ø

Example 27: Compound 33 of Scheme 5 To 1 g of the alcohol 32 in 40 mL of dry ethanol is added a solution of sodium th~obenzoate prepared from 0.2 9 of sodium ~n 10 mL of ethanol and 1.26 g of thiobenzoic acid in 5 mL of ethanol. The reaction mixture is stirred at room temperature for 10 minutes, then ls heated at 45C for an additional 10 m~nutes~
The mixture becomes very thick and difficult to st~r and a yellow product separates. The product, Compound 33 of Scheme 5, is removed by filtration and washed with ~ater. Y~eld 1.2 g, melting point 151-152C; lH
NMR (r~S0-d6/acetone-d6) ~ 7.~-8.3, 3.85, 3.1-3.6.

Example 28: Compound 168 of Scheme 18 -Cyanoacet~c ac~d (8.5 9; 0.1 mol) and N-hydroxy-succ~n~mide (11~5 9; Ool mol) are comb~ned in 150 mL of dry te~rahydrofuran. To the cooled suspension is added dropwise a solution of 20.6 9 (0.1 mol) of dicyclo-hexylcarbodiimide in 50 mL of dry tetrahydrofuran over a period of 2 hours. The mixture ls allowed to warm to room temperature overnight. The wh~te precipitate which forms is removed by filtration and washed with 50 mL of tetrahydro~uran. The tombined filtrates are con-centrated to glve 8 9 (44~ yield) of the ester 167.
The product crystallizes from isopropyl alcohol as white needles, m.p. 140-142C.
A solution of the ester 167 (0.62 9, 3.4 mmol) in 10 mL of dry dimethoxyethane ~s added dropwise to a stirred solution of the cyclic diamine 88 (0.8 9, 3.4 mmol) in 20 mL of dry d~methoxyethane at room temperature. The solutlon ~s stirred for an additlonal 2 hours, after which ~t ~s allowed to stand for 16 hours. The dimethoxyethane is removed by rotary evaporation and the brown residue is susp~nded in water to remove N-hydroxysucclnimide. The product 168 i5 removed by filtration and crystalllzed from toluene/
hexanes as fine brown needles; yleld 0.9 9 (88X); m.p.
142-143C; IR (thin fllm) 3450, 2250, 167S cm~1; 1HNMR
(CDCl3): ~ 3.7) 2.4-3.6~ 3.5, 1.3, 1.25. Anal. Calcd.
for C13H23N3nS2: C, 51.79; H, 7.69; N, 13.94; S, 21.27. Found: C, 51.99; H, 7.12; N, 14.01~ S, 21.34.

Example 29: Compound 169 of S~heme 18 A solution of 3 g of the nitrlle 168 ~n 50 mL of dry tetrahydrofuran is added dropwise over a 30 minute per~od to a stirred slurry of 1.2 9 of lithium alumi-num hydr~de in 100 mL of dry tetrahydrofuran, under anltrogen atmosphere. The pale yellow solution ls heated at reflux for 7 hours, then stirred at room temperature for 50 hours. The slurry ~s hydrolysed with a saturated Na-K tartrate solution, the aqueous phase ~s extracted w~th dichloromethane and the com-b~ned organic extracts are dried over sodium sulfate.
Rotary evaporation of the solution leaves the amine 169 as a viscous yellow oil.

Example 30: Compound 170 of Scheme 18 A solution of the activated ester 16 (~ 9, 9 mmol) in 30 mL of dimethoxyethane is added dropwise over a period of 1 hour to the amine 169 (2.6 9, 8~9 mmol) in 70 mL of dlmethoxyethane. After 1 hour, thin layer chromotography (eluent: petroleum ether/acetone/
d~chlorome~hanel~sopropyl alcohol, 10:5:5:1) indicates one major component hav~ng an Rf of 0.6. The solvent is re-noved by evaporation, the residue is treated with water and the mixture is extracted with chloroform and dried over sodium sulfate. Removal of the solvent leaves 120 as a viscous yellow mass, yield 2.1 9; 1HNMR
(CDC13~ ~ 7.3-9.3~ 2.6-3.6, 1.5.

Example 31: Compound 40 of Scheme 19 To a m~xture of 10 9 of sodium bicarbonate in 50 mL of water and 200 mL of toluene is added the ester 70 (2 9, 0.01 mol), with cooling in an ice-bathO Chloro-acetyl chloride (5 9, 0.44 mol) solution is added drop-wise, then the m~xture ~s allowed to warm to room tem-perature. The organic phase is extrated with ethyl acetate~ washed with water and brine and then dried over magnesium sulfate. Removal of the solvent leaves 40 as a whlte mass; yield 2 9 (70X); m.p. 85-87C.
1HNMR (CDCl3): ~ 7.12, 7.6, 4.67, 4.2, 4707, 3.75, 1.3.

Lxample 32: Compound 41 of Scheme 19 A solutlon of the ester 40 (2 9, 9 mmol) in 20 mL
of dry ethanol is prepared under argon. To this is added a solution of sodium thiobenzoate in dry ethanol (prepared from 0.45 9 of Na In 2~ mL of ethanol to form sodium ethoxide, which is reacted with 2.5 9 of 97%
t,hiobenzo~c acid). Precipitation occurs immediately.
The reaction mixture-is heated at reflux for 5 m1nutes~
then Is diluted with ethyl acetate. The aqueous phase ls extracted with ethyl acetate. The comb~ned organic extracts are washed with water and br~ne and dried over magnesium solvent. Removal of the solvent leaves 4.1 9 of a creamy wh1te powder. Crystalli~ation from toluene gives 2.4 9 of whlte product, 41, m.p. 12S-127C (Lit.
129.5-131C). NMR is consistent with structure, Examp~e 33: Compound 176 of Scheme 19 A mi~ture of todoethanol (7.5 9, 43 mmol~, nicot~nam1de (5.2 g, 43 mmol) and 150 mL of acetone is heated at reflux for 18 hours. The mixture is cooled and the product 176 is removed by filtration. Yield 105 9 (12%); m.p. 87~Co Example 34: Compound 177 of Scheme 20 ~

To a mixture of lO g of potassium carbonate in 20 mL of water and 200 mL nf toluene is added 5 9(32 mmol) of 3,4-diaminobenzoic acid. To the cooled mixture is added 14.4 9 (127 mmol) of chloroacetyl chloride in 10 mL of toluene over a period of 1 hour. After the addi-tion is complete, the mixture is stirred at room temperature for 30 minutes. The brown product ~s removed by filtration and crystallized from ethanol.
Yield ~ g(82%) of 177, m.p. 240-241C.

Example 35: Compound 178 of Scheme 20 _, To 25 mL of ethanol is added 0.17 9 of sod1um metal, followed by 1.1 g (7.4 mmol) of thiobenzo1c ac~d. To the resultant yellow-brown solution is added 1.16 g (3.7 mmol) of the acid 177. The mixture turns yellow lmmediately and thickens. The mixture 1s diluted to 200 mL wlth dry ethanol and heated at reflux for 2 hours. The product is removed by f1ltration and crystallized from isopropyl alcohol/tetrahydrofuran.

Yield 1 9 (53~) of 178, m.p. 244-245C.

Example 36: Compound 179 of Scheme 20 To 15.2 9 (0.03 mol~ of the acid 178 and 3.45 9 (0.03 mol) of N-hydroxysucc~nimide ls added 500 mL of dry tetrahydrofuran. To the resultant suspension is added 6 9 (0.03 mol) of dicyclohexylca~bodlimide in 50 mL of dry ~etrahydrofuran, over a per~od of 1 hour.
The resulting mixture is stirred at room temperatre for 16 hours. The white precipitate of dicyclohexylurea which forms is removed by flltration and the ~iltrate in concentrated in vacuo to give a brown product.
Flash chromatography of a small sample (eluent:
dichloromethane/aetone, 3:1j gives the ester 179, m.p.
117-~118 C.

Example 37: Compound 183 of Scheme 21 A solution of 2-bromoethylamine hydrobromide (10.2 9, 0.05 mol) and nicotinamlde (6 9, 0.05 mol) in 150 mL
of dry dimethylformamide ~s heated at 140C for 16 hours. The precipitate which forms is rernoved by filtrat~on and washed with ether. Yield 14 9 (88~), m.p. 280C tdecomp.) of 183.

Example 38: Compound 75 of Scheme 9 A solut~on of the amine 74 (2 9~ 7.5 mmol) and the activa~ed ester 16 (1.65 9, 7.5 mmol) In 100 mL of dry dimethoxyethane ~s stirred at room temperature for 24 hours. The solvent is removed by rotary evaporation and the residue is treated w~th water. The v~scous product is extracted with chloroform and dried oYer magnesium sulfate. Removal of the solvent leaves 75 as a viscous mass. NMR is consistent with structure. The compound is used without further purification.

Example 39: Compound 76 of Scheme 9 A solution of the amide 75 (0.5 9), 5 mL of methyl iodide and Z0 mL of nitromethane is stirred at room temperature for 7 days under argon. After the second day, a precipitate hegins to form. The precipitate is remuved by flltrat~on and treated with acetone. Yield 150 mg of the quaternary salt 76, m.p. 210-215C
(decomp.) lHNMR (~MS0-d6) ~ 8.3-9.5, 4.5, 3.0-4.0, 1.2-1.5.

Example 40: Compound 77 of Scheme 9 To a solutlon of 0.5 9 (1 mmol) of the quaternary salt 76 in 10 mL of water is added 0.25 9 (3 mmol) of sodium bicarbonate and 0.61 9 (3 mmol) of sodium dithionlte~ ~ther (50 mL) is added and the mixture is stirred under a nitrogen atmosphere for 30 minutes as~

whtle being cooled in an ice-water bath. The aqueous phase ~s extracted with d~chloromethane~ The combined organic phase ls dried over magnesium sulfate.
Obtained in this manner i5 the dlhydro derivative 77.

Example 41: Compounds 81 and 81a of Scheme 10 A solutlon of the ester 7~1 (10 g, 35 mmol) in 100 mL of dry tetrahydrofuran is added dropwise over a priod of 30 minutes to a slurry of lithium aluminum hydride ~4 9, 94 mmol) in 300 mL of dry tetrahydro-furan, w;th cooling in an ice-bath. The slurry is then heated at reflux for 24 hours. The reaction is quenched with saturated Na-K tartrate solution, then with 3N hydrochloric acid and finally with sodium carbonate. The aqueous phase is extracted with chloroform. The combined organic phase is washed with saturated aqueous sodium chloride solution and drled over magnesium sulfate. Removal of the solvent leaves the alcohol 81 as a v~scous mass. The p~oduct is taken up in ether saturated with hydrogen chloride, with cooling in an ice~bath. Yield 6 9 of the sal~ 81a, m.p. l90-191C. NMR and elemental analysls consistent with structure.

Example 42: Compound 190 of Scheme 23 _. ... _, To 24.6 9 (0.17 mol~ of nicotinic acid and 32 9 (0.19 mol) of N-hydroxyphthalimide in 300 mL of tetra-hydrofuran are added 41 9 of dicyclohexytcarbodilmide ~1~6-~n 200 mL of tetrahydrofuran voer a per~od of 2 hours.
The reaction m1xture ~s st~rred at room temperature for 24 hours. The white preclpitate of dicyclohexylurea which forms is removed by filtration. The filtrate is concentrated, leaving a white mass which is crystall-lized twice from ethyl acetate, once from isopropyl-alcohol, and aga~n from ethyl acetate. The Yarious batches of 190 thus obtained melt at 132-135C and 148 150C. lHNMR (CDC13) ~ 8.4-9.5 (m, 3Ht Py-H); 7.95 (s, 4H~ Ar-H); 7.5-7.7 (m, lH, Py-H).

Example 43: Compound 191 of Scheme 23 ~

A solution of the ester 190 (5 9, 18.6 mmol) and methyl iodide (6 g, 42.4 mmol) ~n 40 mL of acetone is placed ~n a pressure bottle and heated in an oil bath (bath temperature 65C) for 12 hours. The product is removed by filtration. Yield 4.5 9 (59~) of the quaternized activated ester 191. The product darkens at 175C and melts at 185~C. lHNMR (DMS0-d6) ~ 8.2 9.9 (m~ 4H, Py-H); 8.1 (s, 4H, Ar-H); 4.52 (s, 3H, N-C~3).

Example 44: Compound 180 of Scheme 21 To the activated ester 179 ~9 9, 14.9 mmol) ln 100 mL of dimethoxyethane is added ethanolam~ne (0.918 9, 15.4 mmol) in 50 mL of dimethoxyethane. The reaction mixture is stirred at room temperature for 48 hours, the white precipitate which forms is then removed by filtration~ Concentration of the solvent gives an additional 2 9 of the product. Yield 4 9 (49~) of 180, melting at 205-21~C. lHNMR (DMS0-d6): ~ 705-10~ 4.8, 3.3-3.7~ 3.3.

Example 45: Compound 179 of Scheme 25 The acid 178 (8 g) and N-hydroxysuccinim1de (1.8 g) are combined in 200 mL of tetrahydrofuran. To that suspension is added dicyclohexylcarbod~imide (3.16 9) ln 25 mL of tetrahydrofuran over a period of 2 hours.
The mixture is then stirred at room temperature for 16 hours. The white precipitate ls removed by filtratlon and the filtrate is concentrated in vacuo. The product, the activated ester }79, is crystall~zed from toluene.

Exmaple 46: Compound 194 of Scheme 25 To 4.7 9 (8 mmol) of the activated ester 179 is added a solution of 0.14 9 (~ mmol) of ammonia in 150 mL of dimethoxymethane. The reaction mixture is stir-red at room temperature for 16 hours. The solutlon ls concentrated ln vacuo to gi~e 3 9 of the amide 194 as a white product.

Example 47: Compound 76 of Scheme 23 To 6.12 9 (23 mmol) of the amine 74 ~n 100 mL of anhydrous dimethylformamide is added dropwise, over a period of 4 hoursg 2.2 9 (6 mmol) ~f the activated ester 17 in 80 mL of anhydrous dimethylformam~de. The react~on is carr~ed out at -47C (acetonitr~le/dry ~ce) while under an argon atmosphere. The reactlon mixture is stirred for an addltlonal 2 hours at -47C, then is placed ;n a freezer (approximately -20C) overn~ght.
The dimethylformamide ~s removed in vacuo. To the residue is added 150 mL of xylene and the solvent is again removed in vacuo. The res~due is taken up ~n 75 mL of benzene and triturated with petroleum ether, after which a gummy product separates. Th~s process is repeated tw~ce. The resultant gummy residue is suspended in the same solvent. ~PLC data indicate one major peak with some amine being present. Flash chromatography (eluent, methanol) of a small sample of the reaction mixture gives a product which by HPLC
~ndicates two components, the residual amine and the desired quaternary salt 76.

Example 48: Compound 76 of Scheme 23 To 1.5 9 (5.7 mmol) of the amine 74 in 20 mL of dimethylformamide ~s added 0.5 9 (1.4 mmol) of the quaternary compound 191 in 20 mL of dimethylforma~
mide. The reaction is carr~ed out at -47C over a two hour period, under an argon atmosphere. The solvent Is re~oved ~r vacuo and the residue 7s ~reated 5 times w~th benzenelpetroleum ether. HPLC data again ind~
cates most of the am~ne has been removed, leaving the des7red quaternary salt 76.

-14g-Exam~ 49: 1-methyl-3 ~N-~{~-{4~ 2'-b~5(4''-methylthiosemlcarbazono)prop-1'-yl]-phenyl}ethyl}}carbamoyl]pyrid~nlum iodide hemihydrate (Compound 222 of Scheme 32) Amino-PTS hydrochloride monohydrate (100 mg, 0.238 mmol) ln dry pyridine (15 mL) with the quaternlzed activated ester 191 ( 200 mg, 0.488 mmol~ is heated at gentle reflux. After 2 hours, no amino-PTS remalns and the mlxture is set aside to cool. Yolatiles are removed in vacuo and the residue is washed ~ith water (10 mL) and taken into chloroform (40 mL). The aqueous layer is re-extracted with chloroform (20 mL) and the combined, dried (MgS0~) onganic layers are evaporated to dryness, leaving an orange oil. The oil is taken into a minimum of warm ethanol. Trituration results in preclpitatlon o~ a pale yellow powder. Y~eld 75 mg (51%) of the quaternary salt 222, melting at 214-216C. IR (KBr) 3000-3600, 1670~ 1~35, 1470 cm~1;
1HNMR (DMS0-d6) C 9O5~ 8.1-9.4, 7.1-7.6, 4.5, 2.3-3.8. Analysls calculated for C22H2gN~IOS 1t2H20: C, 42.51: H, ~.86; N, 18.01; S, 10.31. Found: C, 42.70;
H, 4.77; N, 17074; S, 10.42.

Example 5D: 1-{{4'-{~-[N-(1''-methyl-1''34''-dihydropyridin-3''-yl)carbonylamino]-ethyl}phenyl}}propane-1,2-dlone bis(4-methylthiosemlcarbazone), hydrated with 1/4 mole H20 (Compound 223 of Scheme 32) 3L~67~

-~5~-The quaternary salt 222 (104 mg, 0~17 mmol) in ice-cold deaerated water (30 mL) is treated with sodium bicarbonate (140 mg, 1.7 mmol) and sodium d~th~onite (30 my, 1.7 mmol). Ethyl acetate (50 mL) 1s added to the stirred solution, and nitrogen gas (scrubbed free of oxygen by passing through a bas~c pyrogallol sol~tion) ~s bubbled through the reation mixture.
After 45 m~nutes, the organic and aqueous layers are separated~ and the aqueous layer is re-extractd with ethyl acetate (30mL). The combined organic layers are dr~ed over magnesium sulfate and the volume of solvent is reduced to half by evaporation ~n vacuo. The product is eluted through a short column of neutral alumina (Aldr~chJ 150 mesh, Brockman l)~ Evaporation of the solvent affords the dihydro derivative 223 as a yellow powder. Y~eld 57 mg (70X). The product darkens at 130C and decomposes at 185C. lHNMR (CDCl3/DMS0-d6) ~ 8.0-8.3, 7.1-7.5, 6.95~ 6.0-6.4, 5.6-5.8. 4.5_ 4.8, 3.4~3.7, 3.2, 2.8-3.4, 2.3. Analysls calculated for C22H30N80S2 1/4H20: C, 53.80; H, 6.41; N, 22.82;
S, 13.04. Found: C, 53.80; H~ 6.27; N, 22.63; S, 13.02.

~L26~

The foregoing reac-tion schemes and examples illustrate the preparation of a wide varie-ty of - derivatives of this invention in which the dihydro-pyridine = pyridinium sal.t redox carrier moie-ties can be one of the [DHC]/[QC ] groupings depic-ted on pages 19 to 38 herei.nabove wherein p is zero. The preparation of yet other derivatives of this type will be readily apparent to those skilled in the art from the teachings hereinabove, particularly in light of the illustrative synthetic methods detailed in the International Publication No. W083/03968. Moreover, it is possible to adapt the methods of W083/03968 and of the present specification to the preparation of -the instant derivatives containing the carrier moieties depicted on pages 19 to 38 above wherein p = 1 or 2.
Some illustrative methods for preparing the compounds of this invention in which the carrier Il comprises a [NH-alkylene-C-]p group as depicted Ro hereinabove wherein p = 1 or 2 are set forth below.
It should be noted that just as the p = 1 or 2 derivatives can be made by methods analogous to those depicted in the reaction schemes for the p = 0 derivatives, so, too, the p = 0 deriva-tives can be prepared by methods analogous to those specifically described below for the p = 1 or 2 derivatives. The methods described below must of course be adapted to theparticular chelating agent selected for derivation, in analogous fashion to the reaction schemes depicted above.

lLLUSTRATIYE SYNTHETIC METHODS

1. Methods for Derivat~zing -NH2 or -N~-Functions METHOD A
.

The chelating agent or its protected counterpart (e.g~ 74 in Scheme 9 or 192 in Scheme 24 or 221 ~n Scheme 32) ls reacted with nicotinuric acid chloride, with nicotinuric acid anhydride, or with nicotinuric acid in the prPsence of a suitable coupling agent such as dicyclohexylcarbodiimide, ~n an appropriate organic solvent, to afford the corresponding glycylnicotina-mide, or nicotinuramide. The nicotinuramide is then quaterni~ed, typically by treatment with methyl iodide ~n a suitable organic solvent, to afford the quaternary derivatlve, which is then de-protected if necessary and reduced by treatment with sodium dithlonite or sodium borohydride as generally described hereinabove.
Alternatively, glycine may be first reacted w~th a reagent capable of introducing an amino protecting group such as benzyloxycarbonyl or t-butoxycarhonyl and the N-protected glycine then reacted with the chelating agent or ~ts protected counterpart in the presence of a coupling agent such as dicyclohexylcarbodiimide, followed by removal of the N-protecting group, followed by reaction with n~cotinoyl chloride or nicotinic anhydride9 or with nicotin~c acid in the presence of dicyclohexylcarbodiimide or other suitable coupling agent/ to afford the nicotinuramide. The n~cotinura-mide may then be quaternized and the quaternary de-7~

protected if necessary and reduced as described in the preced; g paragraph.
~ re procedure of the second paragraph of this method ~ay be repeated using picolinic ac~d or its ac~d chloride or anhydrlde, or isonicotir~c acid or its acid chloride or anhydride, in place of nicotinic acid or its acid chloride or anhydr~deD respectively, to con-vert chelating agents or their protected counterparts to the corresponding glycyl picolinamides and glycyl isonicotinamides and then to the corresponding quaterr3ry and dihydro derivatives. The procedure of the flrst paragraph of this method may be similarly adaptedO Moreover, any of these procedures may be repeated, substituting a different amino acid or nicotinic acid derivative thereof for the glycine or nicotinuric acid used above, e.g. replacing glycine with alanine, valine, leucine9 phenylalanine, isoleucine, methionine~ asparagine or glutamine.
Alternatively, the chelating agent or its pro-tected counterpart may be reacted with an activatedester of nicotinuric acid or the like, e.g. a sucinimidyl ester such as ~ ~NHCH2~0H~

and the product quaternized, de-protected lf necPssary and th~ reduced as described in the first paragraph of this m~ hod to afford the identical products. As yet another and highly desirable alternative, the activated ester. ~.9. the siccin~midyl ester depicted above, may be quaternized ~e.g. by treatment with methyl iodide) and the quaternized actlvated ester then reacted with the drug. The quaternary compound thus o~tained may then be de-protected lf necessary and reduced as described ~n the first paragraph of this method.

METHOD B

This method is of particular use when the -NH-function is part of an amide or imide or a very low pKa primary or secondary amine~
The chelating agent (e.g. 52 in Scheme 7) is first reacted with an aldehyde [e.g. formaldehyde, benzalde hyde9 acetaldehyde or chloral (C13CCHO)]; for example, in the case of formaldehyde, one converts the ~NH-function to a N-function and thus forms a suitable bridging group. The resultant compound is then reacted with n~cotinur~c acid in the presence of a suitable dehydrdting agent, or with nicotinuric acid chloride or nicotinur~c acid anhydride, to form the corresponding nicotinur-lc acid ester of the partial formula O O N
CH OCCH NHC~) ~2~

The resultant intermediate is then quaternized and reduced as in Method A. The alternatlve process utiliz1ng an activated ester or quaternary derivative thereof which is described 1n Method A may be ut~lized to advantage here as well.
Alternatively, the steps subsequent to formation of the function may be replaced with steps analogous to ~hose detailed in the second paragraph of Method A.
The procedure of the preceding paragraph may be repeated using picolinic acid or its acid chloride or anhydride, or isonicotlnic acid or its acid chloride or anhydride, in place of nitotinic acid or its acid chloride or anhydride, respectively (as called for ~n the second paragraph of Method A), to convert chelating agents to the corresponding glycyl picolinic acid esters and glycyl ~sonicotinic acid esters and then to the corresponding compounds of this invent~on. Deri-vatives of amino acids other than glycine may besimilarly prepared. See Method A, last paragraph.
As yet another alternativeS the intermediate compound containing the N

~i7~

group or the like may be reacted wlth thionyl chloride to afford the correspondlng compound contalning a -N-or similar group. That derivative may then be reacted with a metall~c salt (especially a silver or thallous salt~ of n~cotinuric acid or the like (formed; e.g. by reacting nicotinur~c acid or the like with fresh silver hydroxide or oxide or with thallous ethoxide). The resultant nicotinuric acid ester of the par~ial formula O O ~--N

- -or like derivative is then quaternized and subsequently reduced as in Method A.

METHOD C

The prooedure of the second paragraph of Method A
is followed, except that removal of the N-protecting ~roup ls followed by reactlon w1th 3-quinollnecar-boxylic acid or its acid chloride or anhydride instead of nicotinic acid or its acld chloride or anhydride~
The procedure of the first paragraph of Method A
may be similar1y adapted to the productiun of the 3-quinolinecarboxylic acid derivatves. Moreover~ Method C ~ay be combined with Method to afford the corres-ponding 3-quinolinecarboxylic acid derivatlves of the type of chelating agent used in that method.
The procedure of the first paragraph of this method may be repeated using 4-isoquinolinecarboxylic acid or its acid chloride or anhydride to convert chelating agents such as those mentioned with Methods A and B tc the corresponding 4-isoquinolinecarboxylic acid derivatives.
The procedure of the first or third paragraph of this method may be repeated, substituting a different amino acid, e.g. alanine~ valine, leucine, phenyl alanine, isoleucine, methionine, asparagine or glutamine, for the glycine used in the first step.
(See Method A, second paragraph).
The general procedures described above may be utilized to provide the 1~2-dihydro derivatives as well as the 1,4-dihydros.

METHOD D

The procedure of the second paragraph of Method A
is followed~ except that a reactant of the formula ~, C~OCH~COOH

~7E3~9 ls used place of nicotinic acid. (That starting material may be prepared by reacting nicot~nic anhydr~de, nicotinoyl chloride or nicotin~c acld w~th glycolic acid.) The for~going procedure can be repeated using picolinic acid or its acid chloride or anhydride, or isonico~inic acid or its acid chloride or anhydride, in place of nicotinic acid or its acid chloride or an-hydride, respectively, in the preparation of the reactant depicted above. This variation affords a reactant of the formula [~COOCH2COOH N~ COOCH2COOH

which can then be used in place of nicotinic acid to prepare derivatives of chelat~ng agents or their protected counterparts such as those rnentioned with Method A.

METHOD E
~ . . .

The procedure of the second paragraph of Method A
is fol)owed, except that a reactant of the formula ~CONI~

~H2)nCOOH

~26~B~

where~n n = 1-3, preferably 2~ is used in place of nicoti^ic acid. (That reactant may be prepared from nicoti amide, e.g. when n = 2~ by reacting 3-lodopr~pionic ac~d with nicotinamide.) The quaternary salt tnus obtained may then be de-protected if necessary and reduced as described ln Method A. See also Scheme 26.
The procedure described above can be repeated using picolinamide or isonicotinamide in place of nicotiramide in the preparation of the reactant depicted above. This variation affords a reactant of the fo^mula ~ ONH2 or (CH2)n~00H ~tH2)nCH

which can then be used in place of nicotinic acid in the procedure of the first paragraph of this method.

II. Methods for Derivatizing -OH Functions METHOD F

The chelatlng agent or its protected counterpar~
(e.g. ~1 of Scheme 10, or the corresponding bisthiazo-lidine is reacted with nicotinuric acld chlorlde, with nicoti uric acid anhydride, or with nicotln~ric acid in the pr~sence of a suitable coupling agent such as dicyc~onexylcarbodiimide, in an appropriate organic 501 vent, to afford the corresponding glycylnicot~nate, or nicotinurate. The nicotinurate is then quaternized, de-protected if necessary and subsequently reduced as described above in Method A. The alternat~ve process utilizing an acgivated es~er or quaternary derivative thereof which ~s descr~bed in Method A may be util~zed to advantage here as well.
Alternatively, glycine may be first reacted with a reagent capable of introducing an amino protecting group such as benzyloxycarbonyl or t-butylcarbonyl and the N- protected glycine then reacted with the chelating agent or its protected counterpart in the presence of a coupling agent such as dicyclohexylcar-bodiimide, followed by removal of the N- pr4tecting group, followed by reaction with nicotinoyl chloride or nicotinic anhydride, or with nicotinic acid in the presence of dicyclohexylcarbodiilnide or other suitable coupling agent, to afford the nicotinurate. The nicotinurate may then be quaternized, de-protected if necessary and the quaternary reduced as described in the preceding paragraph.
The procedure of the second paragraph of this method may be repeated using picolinic acld or ~ts acid chloride or anhydride, or isonicotinic acid or ~ts acid chloride or anhydride, in place of nicot~nic ac~d or ~ts acid chloride or anhydride, respectively, to con-vert ~helating agents to the corresponding glycyl picolinic acid esters or glycyl isonicotinic acid esters and then to the corresponding compounds of the invention. The procedure of tlle first paragraph of this method may be similarly adapted. Moreover, any of these procedures may be repeated~ subst~tuting a different amino acid or nicotinic acid derivative thereof for the glyc~ne or nlcotinuric acid used above, e.g. replacing glycine with alanine, valine, leucine, phenylalanine, isoleucine, methionine, ~sparagine or glutamine.

METHOD G

The procedure of the second paragraph of Method F
is followed, except that ~ reactant ~f the formula [~, CONH2 ~_ (~2)nCH
wherein n = 1-3, preferably 2 (prepared as described in Method E)~ ls used ~n place of nicotin~c acid. The quaternary salt thus obtained may then be de-protected if necessary and reduced as described in Method A.
Method G ~s of particular use in preparing deriva tives of chelat~ng agents in which the hydroxy function is hindered.

Alternatively, Method G may follow Method F, second paragraph, except that it employs a reactant of the ~or~ula J-( H2)nCOOH (C~ ,COOH

~7~
. -162-(prepared as described ~n Method E) in place of nicotinic acid.
The procedures of this method may be repeated, substituting a different amino acid, e.g~ alanine, valine, leuclne, phenylalanlne, isoleucine, methionine, asparagine or glutamine, for the glycine used ;n the first step. (See Method A, second paragraph)~

METHOD H

The procedure of Method F, second paragraph, is followed, except that removal of the N- protecting group is followed by reaction with 3-quinolinecar-boxylic acid or its acid chloride or anhydride instead of nicotinic acid or its acid chloride or anhydride.
The procedure of the ~irst paragraph of Method F
may be similarly adapted to the production of the 3 quinollnecarboxylic acid derivatives.
The procedure of Method H may be repeated using 4-lsoquinollnecarboxyllc acid or lts acid chloride oranhydride in place of 3-quinolinecarboxylic acid or ~ts acid chloride or anhydride.
3-Quino1inecarboxylic acid or its acid chloride or anhydride or 4-isoqulnolinecarboxylic acid or its acid chloride or anhydride can also be substituted for nicotinic acid or its acid chloride in Method B, fourth paragraph, to af~ord the correspondin~ derlvat~ves.

2 ~

The general procedures described aboYe may be utilized to provide the 1,2-dihydro der~vatlves as well as the 1,4-dihydros.

METHOD I

The procedure of the second paragraph of Method F
is followed, except that a reactant of the formula ~, COOCH2COOH

is used in place of nicotinic acid.
A starting material of the formula set forth immediately aboYe can also be substituted for nicotinlc acid in Method B, paragraph 4, to afford the sorres-ponding derivativesO
Alternatlvely, Method I may follow Method F, second paragraph, except that it employs d reactant of the formula ~COOCH2COOH ~- COOCH2COOH

(prepared as described in Method D30 These alternative Method I start,ng materials may be substituted for nicotinic acid ~n Method B, fourth paragraph~ to give the corresponding derlvatlves.

~7~

The procedure of the first or third paragraph of this method ~ay be repeated, substitut~ng a d1fferent amino acid, e.g. alanine~ valine, leucine, phenyl-alanine, isoleucine, methionine, asparagine or glutamine, for the glyc~ne used in the first step.
~See Method A, second paragraph).

III. Methods for Derivatizing -COOH Functions METHOO J

Nicotinuric acid (N-nicotinoylglycine) or an activated ester thereof is reacted with an aminoalkanol H2N-Z'-OH

wherein Z' is C1-Cg straight or branched alkylene, e.g.
2-aminoethanol, tc afford the corresponding inter-med~ate alcohol, e.gO in the case of 2-~minoethanol~ an intermediate of the formula ~ P O
~ CHHCH2CNIICH2CH20H

That alcohol is then reacted with a chelating agent contaln~ng one or more -COOH funct~ors, ~n the presence of a suitable coupling agent such as dicyclohexylcar-bodiimide. The compound thus obtained is thenquaternized and subsequent7y reduced as descr~bed above in Method A.

Nicotinuric acid is commercially available.
Howeve^~ ~t and ana10gous starting mater~als can be readi'~ prepared by react1ng the selected amlno acid wlth t~e acid chloride of nicotinic acid, of plcolinic acld, of isonicotinic acid, of 3-qulnolinecarboxyllc acid~ of 4-~soquinolinecarboxylic acid or the like to afford the desired N-substituted am~no acid, which can then be reacted wlth an aminoalkanol as described above.

METHOD K

The chelating agent is first reacted with ethylene glycol (or other dihydroxyalkanol having up to 8 carbon atoms), in the presence of a suitable coupling agent such as dicyclohexylcarbodi;mide, to convert the -COOH
function(s) to the corresponding (or other -C-O-Z'-OH) group(s). Then, a N-protected amino ac~d, such as N-benzylo~ycarbonylglycinel which has been prepared as descr~bed ;n Method A~ 1s reacted therewith in the presence of dicyclohexylcarbodlimlde or other appropriate coupl1ng agent. Removal of the protec-ing group, e.g. by catalytic hydrogenation, af-fords ~ derlvative of the chelating agent ~n which the origir 1 -COOH group(s) has/have, in the case of utiliz ny ethylene glycol and glycine, been converted to the structure -COOCH2CH2QCCH2N~2 -That intermediate is then reactéd with a compound of the formula ~H2CH2COOH

5 or the like, prepared as described in Me~hod E, in the presence of a coupling agent such as dicyclohexylcar-bodiimide, to give the desired quaternary derivat~ve.
Subsequent reduction to the corresponding dihydro derivative proceeds as d~scribed in Method A.
The procedure described above may be repeated utilizing a reactant of the formula C~HH2 tONH2 (~
CH2tH2COOH I~H~CH~2tOOH
or the like, prepared as described in Method E, ln place of the intermediate of the formula ~H2CH2COOH

METHOD L

A chelating agent contain~ng one COOH function is reacted with an e~uivalent amount o~ inositol, in the presence of dicyclohexylcarbodiim~de or other suitable coupling agent, to convert the -COOH function to a group of the structure (9H)5 Reaction of that intermed~ate with nicotinuric acid, in the presence of a suitable coupling agent9 or with an activated ester of nicotinuric acid, affords an inter-mediate in which the original COOH has been converted to -COO ~OCCH2NHC ~
~OR)4 O O N
whereln each R is H or -CCH2NHC ~ , the number of origiral hydroxy groups esterified varying with the : amount of nicotinurlc acid employed. Subsequent qua-terni7ation and reduction are carried out as in Method A~
Alternatively, the above procedure may be repeat-ed, replacing nicotinuric acid with an analogous starting material, prepare~ by reac~ing the selected amino acid with the ac~d chloride of nfcotinic acid, o~ pico-:~IL2~9 linic acid, or Isonicotinic acid, ~ 3-quinolinecar-boxylic ac~d, of 4-isoquinotinecarboxylic acid or the l~ke.
Repet~tion of the procedure of the f~rst paragraph of this method util~zing a greater amount of the chelating agent (e.g. 2 to 5 or more moles per mole of inositol) provides an intermediate conta~ning from 2 to ~ acid residues and from 4 to 1 hydroxyl groups. That intermediate is then reacted with nicotinurlc acid to convert at least one O O N
hydroxyl group to the corresponding -OCCH2NHC ~ , group. Subsequent formation of the quaternary and reduction proceed as in Method A.

METHOD M

The chelating agent is first reacted with 1,2-propylene glycol (or other dihydroxyalkanol hav~ng up to 8 carbon atoms)p ~n the presence of a suitable coupling agent such as dicyclohexylcarbodlimide, to convert the -COOH function(s) to the correspondlng -CO~CH~CHOH

R

~or other -C-O-Z'-OH) group~s). The resultant inter-78~
-169~

mediate is then reacted with nicotinuric ac~d, ln the presence of an appropriate coupllng agent, or with an activated ester of nicotinurlc acid, to g~ve an inter-medlate of the partlal formula O O N
-COOCH2C~O~CH2HHC ~>

Subsequent quaternization and reduction are carried out as in Method A.
Alternatively, the above procedure may be repeat~
ed, replacing nicotinuric acid with an analogous star~-ing material 7 prepared by reacting the selected aminoacid with the acid chloride of nicotinic acid, of pico-linic acid, of isonicotinic acid9 of 3-quinolinecar-boxylic acid, of 4-isoquinolinecarboxlic acid or the like.

METHOD N
.

Glucosamine, of the structural formula c~2o~l ~O~H
#0~ ' is reacted with nicotinuric acid, using equimolar amounts of the reactants, in the presence of a suitable coupling agent such as dicyclohexylcarbodiimide, or ~ ~ 6 7~9 with ~n activated ester of nicotinuric acid~ The resultant intermediate of the formula ÇH20H

~ ~ N
HHCCH2NHC ~

ls then reacted with a chelating agent containing one reactive -COOH function, în the presence of dicyclo-hexylcarbodiimide or other appropriate coupling agen~D
replacing one or more of the hydroxy groups with acid residue(s) t the number of groups replaced varying with the relative amounts of reactants used.
Alternatively, the above procedure may be repeat-: ed, replacing nicotinuric acid with an analogous start-ing material, prepared by reacting the selected amino acid wlth the acid chloride of nicotinic acid, of pico-linic acid, of isonicotinic acid, of 3-quinolinecar~
boxylic acidt o~ ~-isoqu~nolinecarboxylic acid or the llke.

Sultable nontoxlc pharmaceutlcally ~cceptable d~luents or veh~oles for use w1th the present csmplexes of fon~ula ~ ) w1ll be apparen~ to those sk117et ln th1s art. See. ~or example, Remington's Pharma-seut~cal Sc1ences~ 4th Ed~t~sn tl9703. Obvious~y~
the cho1ce of suitable dfluents or veh~c~es will depend upon the exact na~ure of the particular dosage form selected.
The dosage ranges for adminis~ration of the com-plexes according to ~his invention will vary with the s~ze and spec~es of the su~ject, the objective for which the ~omplexis adminis~ered, the particular dosage form emp70yed, and the like; as discussed below.
The quantity of given dosaqe form needed to deliver the desired dose of the radiopharmaceutical. of course, depends upon the concentrat~on of the complex ~n any g~ven pharmaceut~cal composition/dosage form thereof and the radioactiYity thereof.
By way of example onl~, ~ 5-50 mg/kg dose of formula (III~ radiopharmdceutica? ~ ~njected fnto the tail ve1n or carotid ve1n o~ rats9 due to the ~lock ~n"
mechanism w111 exhlb1t a very significant difference between bra~n and perlpher.a7 7evels o~ rad~oact1v~ty, w~th-consequen~ ready radio~ma~ng of the bra~n;
imag~ng d~ approximately 60 ~co 90 minutes ~fter admfnlstration w~ll be most effective~ since ~ will take adYan~age o~ th~s br~n~per~pheral ~ferent~al~

The 1nstant r~d~ophAr~aceut~cals ~re generally adm1nlstered 1ntr~venously. Sustained rel~ase ~d-~1nfs~rat10n, typ~cally by slow intravenous ~nfusion, ~117 f~r~her enhance the s1~e-spec1f~city of the ~nst~nt redox system. The rate of release of the formula ~I.II) rad~opharmaceutfcal from the susta~ned release system should be comparable ~o the rate of in vivo nxidat~on of the d1hydro form ~ to he quaternary form (~Y) ~n order to ach1eve the greatest degree of enhancement 10 of spec1f~cfty.
-In a further ~spect~ the present ~nvent10n also prov1des a process for the manufacture o~ a diagnostic a~ent for ~he visual~zat~on o~ an organ sueh as the bra1n. To that end, the b~ood-brain barr~er penetrating for~, formula (III~, ~s admixed with an aqueous buffer med1um hav1n9 a pH value of about 4 to about 8 preferably of about 6.5 to abou~ 7.5, in an effect1Ye rad101mag1ng a~ount.
Preparat10n of the rad10pharmaceutic~1 can be carr~ed out in the hosp~tal or ~ike loca~10n where the pat1ent ls found 1n order to minim~ze losses of rad10~ctly1ty caused by the decay o~ the radloactive meSa7.
Inasmueh as the preparat~on for visualization is ~n-~ectable, ~t must be ster~le a~d pyrogen free; pre~erably~
1t ~s ~lso 1sotonic. To ~his end, a so-called labeling k~t can be prov1ded tha~ permits a s~mplel, rap1d and sAfe l~bel irlg of tl~e solut~on to be in jected with the rad~oactive me~al, e.~ echnetium-99m. Sllch k~ts are espec~ally desirable ~hen a short-lived radio-30 1sotope such as technet~um 99 m 1s used.

-173~

~he k~t lncludes ~ co11ect~ng v~al for rece1Y~ng and/or conta~n~ng an a~ueous med~um in which the com-plex~ng react~on can be ef~ected. Additlonally, the kit 1ncludes the chelat~ng agen~ of formu1a (II) or s chelat~ng agent precursor of formula (I~ and a pharma-colsg~ca~ly ~cceptable reduc1ng agent for reducing the radioact~ve ele~ent to an appropriate oxidat~on state for complexing with ~he chelat~ng agent ~and also for reduclng the pyr~d~nium sarrier moiety to the correspond~ng dihydropyr~dine formD when a chelating agcnt precursor of formula (I) 1s present].
In the casc of.technet~um-99m, the rad~oactive element ~s received from a radionuc~de ~enerator as an aqueous pertechnetate (TcOi) solut~on such as an eluate ~n isotonic saline, as is well-known in the ar~. The amount of Tc-99m required to produce a quant~ty of ~ormula (IiI) radiopharmaceutical suf-f~c~ent for d~agnostic purposes is generally from 0.01 m~ Cur~e (mC;) ~o about 500 mCi per ml of 99m pertechnetate solut1On~ The reduG~ng agent for the pertechnet~te can be ~ th~osulfate or dith~on1te 1f She reduc~ng react~on ~s ~o be carr~ed out ~n a bas~c nled1um, or a tln (II) salt such as SnC12 if the reducing re~ct~on 1s ~o be carrfed cut 1n an ac1d Inediuml A k~t for prepar~ng ~n ~n~ectable radlopharma-ceutica1, e.g., for complexing an organ-spec~f~c agent labe7ed with a rad10active metal D 1ncludes, ~n separate containers: Il) a b~ologically compat~ble, sterile aqueous mediu~ su~tabl~ ~or complex formation with a rad~oact~ve me~al 9 ~2J a d~hydropyr~din~ 'pyrfd.in~um ~z~

salt c~rr1er-con~a~nlng eomplex~ng ~gent of farmul~
(I) ~r (II) compat~b1e therew~th, and (3) a pharma-ceu~.cally acceptable reduc~ng agent for the radio-act.le ~etal.
The d~hydropyr1d~ne = pyr1din~um salt carrfer mo~ety ~ay be pres~nt.1n the k1~ e1ther ~n lts ox~dized or 1ts reduced state, ~s tes1red. The reducin~ ~gent for the rad~oact~ve metal can be selected to reduce also the ox1dlzed c~rr~er moiety, ~f present~ as the radloact1ve ~etal ~s reduced to form the complex pre-para~ory to 1n~ctlon of the radlopharmaceut~cal ~nto a tert anlmal or a pat~ent. In a preferred embodiment of ~ls ~nvent10n, a reduclng agen~ capable of reduc1ng both the oxldfzed form of the earrier molety and the rad10act1Ye metal ~s chosen and the chel~ting agent precursor; of formula (~) is present in the kft. In an espec1ally preferred embodlment the kit compr~ses~
~n separate contalners ~preferably ~sep~lcally and hermet~cally sealed v~als of approximately 5-25 ml volume~ a blolog~cally compat~ble, ster~1e aqueous med~um, ~2) d chelatfng agen~ precursor of formu~a (I), (3) a pharmacolog~cally accep~able reduclng ~gent capable of reduc1ng ~che chelatlng agent PreclJrsor of for~ula (I) to a chelat~ng a8ent of formul~ (II) and ~lso capable of re~uc~ng the radloac~1ve metal to ~n ox~dat10n state 1n wh~ch 1t 1s capable of complex~ng w1th ~he formula (~) chelat~ng agent ~o form a ra~io~
ph~rm. :eut~cal of formul~ (III). Most preferably.
the r 'ucing ~gent ~s sodium d~thionite; also most 30 prefe :bly, the rad~oac~l~e metal ls technetium. The d1thlc-lte reduct~on ~s preferably carried out ln ~as~c ~edium; th~s ~ay ~e accompl ished by proYid1ng that the ~queous nled1um (13 ~bove is of bastc pHr -17~-- or by ~dd1ng ~n ~ppropr~ate base ~e.g. NaOH, H ~ 03) when combin~ng the ki~ components and the pertechnet~te solution. As yet another alternative~ the klt could comprise only two separate components: (1) the bio-loglcally compa~ble, sterile aqueous medium of es~
sent~ally neutral pH oonta~n~ng the.chelating agent prec~rsor of formula (I); and (2) the reducfng agent and the base, e.g. sodium dithionite and sodium carbonate.
Radioact~ve metal ~ons are typically not provided w1th the k~t due to the relatively thort half-lives of commonly u~ilized rad~onuclides. Rather, the radio-nucl1de ~s provided separately as described earlier.
and admixed w~th the components of the kit shortly before use, as ~s known for other radiopharmaceutical del~very systems. In the ca~ of technetium-g9m , the pertechnetate solution and ~he basic aqueous medium may be f1rst comblned and then heatedl e.g. from 40 to 95C. for 10 to 20 minutes, in the presence of the reducing agent~then cooled to abou~ room temperature or below prior to addition of ~he formula ~I~ precursor.
In this instance, the techne~ium will be reduced pr10r to reductlon of the ~u~ternary moie~y to ~he correspond-ing dihydro Porm in wh1ch c~se a substantla1 port10n of the quaternary salt (I~ will l~kely chelate with the reduced technet~um to form the quaternary complex (IY~ in the reaction mlxture as an intermediate to the dihydro complex (~II), rather th~n ~he quaternary salt (I~ being firs~ converted to the dihydro chelating agent (~l) and then ~o the dihydro complex (III).
Alternatively, if only ~inimal or no heating is done, the preoursor may be present in the initial mixture made frsm ~he kitt and it is likely in this ins~anoe that the formula (~) qua~ernary will be firs~ reduoed to the formula ~I~J d~hydro~ wh~ch w~l~ then chelate with the reduced technetium to form the complex (~II).
If the mfxture is mildly basic, e.g. pH 8 to 9, it ~ay be administered as ist after the reduction and che~ation have occurred ~o form the formula (III) radlophar~aceutical, or the pH may be adjusted to ~bout 7. If the mixture ~s more s~rongly basic, e.g.
pH 13, 1t 1s generally des1rable to adjust the pH
to a s119h~1y alkal~ne or neutra9 value.
l~h~tever the exact conf19urat10n of the k1t, 1t ~s preferab le for ~ to contain excess ohelating agent precursor (I) or cllelating agent (I~) with respec~
to the rad~onucl1de 'co be complexed therewith. ~.9 ~ 1:2 molar excess. The reducing agent is present in a lar~e excess wi~h respect to the chelating agent precursor (I), e.g. I:S to 1:10. When the chelating -agent (II) rather than the Precursor (I) 1s present, then the reduc~ng agent ls preferably present 1n a sl~.~ht excess w1th respect to the radionuclide.
To effect v~sual~zat1On, the diagnost1c agent is adm1n~stered ~o a patient~ typical7y lntravenously.
wlth or w~hou~ further d~lut10n by a carr1er vehicle such as physlolog~cal s~llne, phosphate-buffered sal~ne, p1as~a, or ~he l~ke. Generally~ the un~t dose to be adm1n~stered has ~ radioaot~vity of about 0.01 ~1171Cur~e (mCI) to about 100 ~ Cur1es, pre~erably ~bout 1 mC1 to ~bout 20 ~Ci. The solu~ion to be injected into an adult pat~ent per unit dosage is about 0~01 ~111111ter (ml) to ~out 1 mill~liter~

After 1nt~Yenous ~dminlstrat~on, ll~ag1ng of the orgari -1n v~vo can t~ke place after a few m1nutes.
If des1r.edD lmaging can ~lso take place hours after the ln~lect10n, depend1ng upon the half-l 1fe of the S radloactlve ~na~er~al that has been ~ntroduced ~nto the patîent and upon the amount of such material ~ntroduced.
Preferably, lmag~ng t~kes place 60 to ~0 ~inu~es after ~ntravenous adm~nistratlon.
Any conYent~ona~ method of ~maging for dia3nostic I0 purposes can be u~llzed ~hen practic~ng the present ~nventlon.
In summary~ then, In 1ts broadest aspects the present 1nYention can ~e seen to provfde compositions of matter comprlsing~ he residue of a che~ating agent havlng at least one reactive funct10nal group selected from the group consisting of amino, carboxyl, - hydroxyl, amide and lm1de, said ~unctional group be~ng not essentia~ for the complexing properties o~ said chelating agent, said residue being characteri~ed by the absence o~ a hydrogen atom from ~t least one of sald reactive functiona~ groups of said chela~ing agent, s~1d chela~1ng agent be1ng either (a~ c~pable of che~at1ng w1th a me~all~c radionuclide or (b) chelated with a metal11c r~d10nucl1de; ~nd (2) ~ d1hydro-pyrld1ne--~pyr~din~um salt redox carrier moiety; said chelating agen~ residue and said carr1er moiety being coupled to eaeh ~ther to form a hydrolyt1cally cleavable 11nkage between.
~h11e the lnventlon has been descrlbed ~n terms of various preferred embo~iments, the skilled ar~isan wlll ~ppreclate tha~ various modifications, substi-tutions, omiss~ons, and changes may be made WithOUt depart~ng from t~e sp~r~t thereof. Ac~ord~nglyl ~t ls intende~ that the scope of ~he present invention 35 be l~m1~ed solely by the scope of the following cla~ms.

Claims (47)

The embodiments of the invention in which an exclusiv~ property or privilege is claimed are defined as follows:

1. A salt having the structural formula (I) wherein is the residue of a chelating agent capable of chelating with a metallic radionuclide, said chelating agent having at least one reactive functional group selected from the group consisting of amino, carboxyl, hydroxyl, amide and imide, said functional group being not essential for the complexing properties of said chelating agent, said residue being characterized by the absence of a hydrogen atom from at least one of said reactive functional groups of the chelating agent; y is 1 or 2; [QC'] is the hydrophilic, ionic pyridinium salt form of a dihydropyridine ? pyridinium salt redox carrier; X is the anion of a pharmaceutically acceptable organic or inorganic acid; n is the valence of the acid anion; and m is a number which when multiplied by n is equal to y.

2. A salt as defined by Claim 1, wherein said residue is characterized by the absence of a hydrogen atom from at least one amino or hydroxyl reactive functional group of the chelating agent.

3. A salt as defined by Claim 2, wherein y is 1.

4. A salt as defined by Claim 3, wherein [QC+] ls a radical of the formula , , (a) (b) , , (c) (d) , , (e) (f) or , (j) wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; RO is a radical identical to the corresponding portion of a natural amino acid; p is O, 1 or 2.

provided that, when p is 2, then the alkylene groups can be the same or different and the RO radicals can be the same or different; R1 is C1-C7 alkyl, C1- C7 haloalkyl or C7-C10 aralkyl; R3 is C1 to C3 alkylene; X is -CONR'R'' wherein R' and R'', which can be the same or different, are each H or Cl-C7 alkyl, or X is -CH=NOR''' wherein R''' is H or C1-C7 alkyl; the carbonyl-containing groupings in formulas (a) and (c) and the X substituent in formula (b) can each be attached at the 2, 3 or 4 position of the pyridinium ring; the carbonyl-containing groupings in formulas (d) and (f) and the X substituent in formula (e) can each be attached at the 2, 3 or 4 position of the quinolinium ring; and the carbonyl-containing groupings in formulas (g) and (j) and the X substituent in formula (h) can each be attached at the 1, 3 or 4 position of the isoquinolinium ring.

5. A salt as defined by Claim 4, wherein p is zero.

6. A salt as defined by Claim 4, wherein p is one, alkylene is -CH2- and RO is H, -CH3, -CH(CH3)2, -CH2-CH(CH3)2, , ,-(CH2)2-SCH3, -CH2-CONH2 or

7. A salt as defined by Claim 1, wherein said residue is characterized by the absence of a hydrogen atom from an -NH-moiety which is part of an amide or imide functional group or which is ,part of a low pKa primary or secondary amino functional group.

8. A salt as defined by Claim 7, wherein y is 1.

9. A salt as defined by Claim 7, wherein [QC+] is a radical of the formula , , (k) (l) , , (m) (n) , , (o) (p) , , (q) (r) or , (s) -l82-wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; R? is a radical identical to the corresponding portion of a natural amino acid; p is O, 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different and the RO radicals can be the same or different; R1 is C1-C7 alkyl, C1-C7 haloalkyl or C7-C10 aralkyl; R is hydrogen, C1-C7 alkyl, C3-C8 cycloalkyl, C1-C7 haloalkyl, furyl, phenyl, or phenyl substituted by one or more halo, lower alkyl, lower alkoxy, carbamoyl, lower alkoxycarbonyl, lower alkanoyloxy, lower haloalkyl, mono(lower alkyl)carbamoyl, di(lower alkyl)carbamoyl, lower alkylthio, lower alkylsulfinyl or lower alkylsulfonyl; R3 is C1 to C3 alkylene; X is -CONR'R'' wherein R' and R'', which can be the same or different, are each H or C1-C7 alkyl, or X is -CH=NOR''' wherein R''' is H or C1-C7 alkyl; the carbonyl-containing groupings in formulas (k) and (m) and the X
substituent in formula (l) can each be attached at the 2, 3 or 4 position of the pyridinium ring; the carbonyl containing groupings in formulas (n) and (p) and the X substituent in formula (o) can each be attached at the 2, 3 or 4 position of the quinolinium ring; and the carbonyl-containing groupings in formulas (q) and (s) and the X substituent in formula (r) can each be attached at the 1, 3 or 4 position of the isoquinolinium ring.

10. A salt as defined by Claim 9, wherein p is zero.

11. A salt as defined by Claim 9, wherein p is one, alkylene is -CH2- and RO, is H, -CH3, -CH(CH3)2, -CH2-CH(CH3)2, , , -(CH2)2-SCH3, -CH2-CONH2 or -CH2CH2-CONH2.

12. A salt as defined by Claim 1, wherein said residue is characterized by the absence of a hydrogen atom from at least one carboxyl reactive functional group of the chelating agent.

13. A salt as defined by Claim 12, wherein y is l.

14. A salt as defined by Claim 12, wherein [QC+] is a radical of the formula , , (i) (ii) , , (iii) (iv) , , (v) (vi) , , (vii) (viii) _ or (ix) wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; RO is a radical identical to the corresponding portion of a natural amino acid; p is 0, 1 or 2, provided that, when p is 2, then the alkylene groups can be the same or different and the RO radicals can be the same or different; Z' is C1-C8 straight or branched alkylene; Q is -O- or -NH-; R, is C1-C7 alkyl, C1-C7 haloalkyl or C7-C10 aralkyl; R3 is C1-C3 alkylene; X is -CONR'R'' wherein R' and R'', which can be the same or different, are each H or C1-C7 alkyl, or X is -CH=NOR''' wherein R''' is H or C1-C7 alkyl; the X substituent in formula (ii) and the carbonyl-containing groupings in formulas (i) and (iii) can each be attached at the 2, 3 or 4 position of the pyridinium ring; the X substituent in formula (v) and the carbonyl-containing groupings in formulas (iv) and (vi) can each be attached at the 2, 3 or 4 position of the quinolinium ring; and the X substituent in formula (viii) and carbonyl-containing groupings in formulas (vii) and (ix) can each be attached at the 1, 3 or 4 position of the isoquinolinium ring.

15. A salt as defined by Claim 13, wherein [QC+] is a radical of the formula , , (x) (xi) (xii) or (xiv) or (xiv) wherein is the skeleton of a sugar molecule; n? is a positive integer equal to the total number of -OH functions in the sugar molecule from which said skeleton is derived; nv is a positive integer one less than the total number of -OH functions in the sugar molecule from which said skeleton is derived; each A
in each of structures (xii), (xiii) and (xiv) can independently be hydroxy or D', D' being the residue of a chelating agent containing one reactive -COOH functional group, said residue being characterized by the absence of a hydrogen atom from said -COOH
functional group in said chelating agent; and each R'4 in each of structures (x) and (xi) can independently be hydroxy, , or D', wherein the alkylene group can be straight or branched and can contain 1 to 3 carbon atoms; RO is a radical identical to the corresponding portion of a natural amino acid; p is 0, ] or 2, provided that, when p is 2, then the alkylene groups can be the same or different and the RO radicals can be the same or different; D' is defined as with structure (xii), (xiii) and (xiv); R, is C1-C7 alkyl, C1-C7 haloalkyl or C7-C10 aralkyl; and the depicted carbonyl-containing groupings can be attached at the 2, 3 or 4 position of the pyridinium or quinolinium ring, or at the 1, 3 or 4 position of the isoquinolinium ring; with the proviso that at least one R'4 in each of structures (x) and (xi) is , or , wherein alkylene, RO, p and R1 and the position of the carbonyl-containing groupings are defined as above; and with the further proviso that when more than one of the R'4 radicals in a given compound are the aforesaid carbonyl-containing groupings, then all such carbonyl-containing groupings in said compound are identical.

16. A salt as defined by Claim 14, wherein p is zero.

17. A salt as defined by Claim 15, wherein p is zero.

18. A salt as defined by Claim 14 or 15, wherein p is one, alkylene is -CH2- and RO is H, -CH3, -CH(CH3)2, -CH2-CH(CH3)2, , , -(CH2)2-SCH3, -CH2-CONH2 or -CH2CH2-CONH.

19. A salt as defined by Claim 4, wherein R1 is methyl.

20. A salt as defined by Claim 4, wherein R1 is -CH2CH2-.

21. A salt as defined by Claim 4, wherein X is -CONH2.

22. A salt as defined by Claim 4, wherein the X and carbonyl-containing groupings whose ring positions can vary are located in the 3 position of the pyridinium ring, in the 3 position of the quinolinium ring system, or in the 4 position of the isoquinolinium ring system.

23. A salt as defined by Claim 4, wherein the carrier moiety is a radical of formula (a).

24. A salt as defined by Claim 23, wherein the carrier moiety is a radical of the formula .

25. A salt as defined by Claim 9, wherein R1 is methyl.

26. A salt as defined by Claim 9, wherein the X and carbonyl-containing groupings whose ring positions can vary are located in the 3 position of the pyridinium ring, in the 3 position of the quinolinium ring system, or in the 4 position of the isoquinolinium ring system.

27. A salt as defined by Claim 9, wherein R is hydrogen, C1-C7 alkyl, C3-C8 cycloalkyl, C1-C haloalkyl, furyl or phenyl.

28. A salt as defined by Claim 14, wherein Z' is C1-C3 straight or branched alkylene.

29. A salt as defined by Claim 28, wherein Z' is C2-C3 straight or branched alky1ene.

30. A salt as defined by Claim 14, wherein the X and carbonyl-containing groupings whose ring positions can vary are located in the 3 position of the pyridinium ring, in the 3 position of the quinolinium ring system, or in the 4 position of the isoquinolinium ring system.

31. A salt as defined by Claim 15, wherein the carbonyl-containing groupings encompassed by the definition of R'4 are located in the 3-position of the pyridinium ring, in the 3 position of the quinolinium ring system, or in the 4 position of the isoquinolinium ring system.

32. A salt as defined by Claim 4, 5 or 6, having the structural formula (Ia) wherein each R5 is independently selected from the group consisting of H and C1-C7 alkyl, or an R5 can be combined with the adjacent such that represents ; each R6 is independently selected from the group consisting of H and C1-C7 alkyl, or an R6 can be combined with the adjacent such that represents ; is a radical of the formula , or wherein each R7 is independent1y selected from the group consisting of H and C1-C7 alkyl; (alk) is a straight or branched lower alkylene group which additionally may contain 1, 2 or 3 oxygen atoms in the chain, said oxygen atoms being nonadjacent to each other and also being nonadjacent to -A1-; X is the anion of a pharmaceutically acceptable organic or inorganic acid; n is the valence of the acid anion; m' is a number which when multiplied by n is equal to one; s is zero or one; -A1- is -NH-, -O- or wherein R8 is C1-C7 alkyl; and [QC+] is as defined in Claim 4, 5 or 6.

33. A salt as defined by Claim 9, having the structural formula (Ia) wherein each R5 is independently selected from the group consisting of H and C1-C7 alkyl, or an R5 can be combined with the adjacent such that represents ; each R6 is independently selected from the group consisting of H and C1-C7 alkyl, or an R6 can be combined with the adjacent such that represents ; is a radical of the formu1a , or , wherein each R7 is independently selected from the group consisting of H and C1-C7 alkyl; (alk) is a straight or branched lower alkylene group which additionally may contain 1, 2 or 3 oxygen atoms in the chain, said oxygen atoms being nonadjacent to each other and also being nonadjacent to -A2-; X is the anion of a pharmaceutically acceptable organic or inorganic acid; n is the valence of the acid anion; m' is a number which when multiplied by n is equal to one; s is zero or one; -A2- is -CONH- or wherein R9 is C1-C7 alkyl; and [QC+] is as defined in Claim 9.

34. A salt as defined by Claim 14 or 15, having the structural formula (Ia) wherein each Rs is independently selected from the group consisting of H and C,-c7 alkyl, or an Rs can be cornbined with the adjacent such that represents ; each R6 is independently selected from the group consisting of H and C1-C7 alkyl, or an R8 can be combined with the adjacent such that represents ; is a radical of the formula or , wherein each R7 is independently selected from the group consisting of H and C1-C7 alkyl; (alk) is a straight or branched lower alkylene group which additionally may contain 1, 2 or 3 oxygen atoms in the chain, said oxygen atoms being nonadjacent to each other and also being nonadjacent to -A3-; X is the anion of a pharmaceutically acceptable organic or inorganic acid; n is the valence of the acid anion; m' is a number which when multiplied by n is equal to one; s is zero or one; -A3- is -COO-; and [QC+] is as defined in Claim 14 or 15.

35. A salt as defined by Claim 4, 5 or 6, having the structural formula (Ib) wherein R1 and R2 are each H or C1-C3 alkyl, n' is an integer of O
to 3 and [QC+] is as defined in Claim 4, 5 or 6

36. A salt as defined by Claim 4, 5 or 6, having the structural formula (Ib') wherein [QC+] is as defined in Claim 4, 5 or 6.

37. A salt as defined by Claim 1, having the structural formula ;

;

;

;

;
;

1-; ;

1-; 1-;

; ;

1- 1-; ;

1- ; ;

;

Br ;

Br' ;

1-;

; or

38. A kit for preparing an injectable radiopharmaceutical comprising, in separate containers: (1) a salt of formula (I) as defined by Claim 1; (2) a pharmaceutically acceptable reducing agent capable of reducing said salt to the corresponding compound of the formula (II) wherein and y are as defined in Claim 1 and [DHC] is the reduced, biooxidizable, blood-brain barrier penetrating form of a dihydropyridine - pyridinium salt redox carrier, said reducing agent also being capable of reducing a radioactive metal to an oxidation state in which said metal is capable of complexing with said compound of formula (II); and (3) a biologically compatible, sterile aqueous medium.

39. A kit as claimed in Claim 38, wherein the radioactive metal which said reducing agent is capable of reducing is technetium.

40. A kit as claimed in Claim 38, wherein said reducing agent is sodium dithionite.

41. A kit as claimed in Claim 38, wherein said aqueous medium is of basic pH.

42. A kit for preparing an injectable radiopharmaceutical comprising, in separate containers: (1) a salt of formula (I) as defined by Claim 1, in a biologically compatible, sterile aqueous medium; and (2) a pharmaceutically acceptable reducing agent capable of reducing said salt to the corresponding compound of the formula (II) wherein and y are as defined in Claim 1, and [DHC] is the reduced, biooxidizable, blood-brain barrier penetrating form of a dihydropyridine - pyridinium salt redox carrier, said reducing agent also being capable of reducing a radioactive metal to an oxidation state in which said metal is capable of complexing with said compound of formula (II).

43. A kit as claimed in Claim 42, wherein the radioactive metal which said reducing agent is capaole of reducing is technetium.

44. A kit as claimed in Claim 42, wherein said reducing agent is sodium dithionite.

45. A kit as claimed in Claim 42, wherein said aqueous medium is of approximately neutral pH.

46. A kit as claimed in Claim 42, wherein (2) contains a base in addition to said reducing agent.

47. A process for preparing a salt of formula (I) as defined by Claim 1, said process comprising: reacting a chelating agent or protected derivative thereof having at least one reactive functional group selected from the group consisting of amino, carboxyl, hydroxyl, amide and imide, said functional group being not essential for the complexing properties of said chelating agent, with a reagent capable of replacing a hydrogen atom from at least one of said reactive functional groups with a [QC+] radical, or with a radical capable of being quaternized to afford a [QC+]
radical; followed by quaternization, when said hydrogen atom has been replaced with a radical capable of being quaternized to afford a [QC+] radical; followed by, when said protected derivative has been used as the starting material, removal of the protecting group or groups to afford the corresponding salt of formula (I).