NZ240145A - Free radical methylcephalosporin-1,1-dioxide derivatives - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £40145 240 14 5 Priority Dsl6{s):..

Co it; te r,- -s.'e.v.ion Filed: Cii>r ■: ."/..canC^Oj.^W-vlS.,JfeOf ^ 0, .,. .. 2 '5feb iy</2 ' ' A303 DIVIDED OUT OF APPLICATION No. 230640 NO WW® PATENTS ACT. 1953 Under the provisions of Regulation 23 (1) the Specification has been ante-dated to...'..... 13 September 1989 COMPLETE SPECIFICATION PROCESS POR 1-CARBA(DETHIA)CEPHALOSPORINS 19 Initials ! — " <' B <r." r: , ; -8 ocr 1091 1' r r < \ JEJ'We. ELI LILLY AND COMPANY, a corporation of the State of Indiana, United States of America, having a principal place of business at Lilly Corporate Center, City of Indianapolis, State of Indiana, United states of America, hereby declare the invention for which 3^/ we pray that a patent maybe granted to me-/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - (followed by page 1A) 240 14 5 -1A- PROCESS FOR l-CARBA(DETHIA)CEPHALOSPORINS This invention relates to free radical compounds of the formula A COO A and their use in a process for preparing 1-carba(delthia)cephalosporin antibiotic compounds. In particular, it relates to a free radical process for converting a cephalosporin 1,1-dioxide to a 1-carba(dethia)cephalosporin.

The 1-carba(dethia)cephalosporins have been obtained by total synthesis, for example, Christensen et al., U.S. Patent No. 4,226,866, describe the preparation of 3-substituted methyl 1-carbacephalosporins, while Evans et al., U.S. Patent No. 4,665,171, describe an asymmetric total synthesis. The l-oxa(dethia)ceph-alosporins and the cephalosporins themselves have undergone extensive investigation and numerous therapeutically-useful antibiotics of these types have been developed. The 1-carba(dethia)cephalosporins have not been readily available for like investigation. Accordingly, methods for the preparation of the 1-carbacephalosporins are much sought after, particularly, methods which are amenable to large-scale production.

The reader's attention is directed to New Zealand Patent Specification No. 230640 which provides a process for converting a 2-substituted-methylcephalosporin 1,1-dioxide directly to a 1-carba(dethia)cephalosporin via free radical 240 1 4 5 X-7280 -2- intennediates. A 2-substituted-methylcephalosporin wherein the substituent is a free radical precursor, e.g., a phenylseleno group, is reacted with a free radical initiator such as a trialkyltin hydride, a 5 triaryltin hydride, a trialkyl or triarylgermane to provide the 1-carba(dethia)-3-cephem-4-carboxylic acid or ester thereof.

The 1-carba(dethia)-3-cephem product can be converted to the desired l-carba-3-cephem antibiotic or, 10 in certain instances, the desired antibiotic is directly obtained from the process.

According to the process of that invention, a 2-substituted-methylcephalosporin 1,1-dioxide represented by formula 1 COOA wherein Z is a divalent group represented by the formulae 240145 X-7280 -3- R is amino, acylamino, protected amino, or Ci-C4 alkyl-sulfony1amino; Rx is hydrogen or C!-C4 alkoxy; Y is a free radical precursor group; R2 is hydrogen, Cx-C6 alkyl, C2-C6 alkenyl, halogen, C!-C4 alkoxy, Cx-C4 alkylthio, tri(C1-C4 alkyl)-silyloxy, C2-C6 alkanoyloxy, C:-C4 alkylsulfonyl-oxy, trifluoromethylsulfonyloxy, or a substituted methyl group represented by the formula -CH2R2' wherein R2' is hydroxy, C1-C6 alkoxy, Cj-Cs 15 alkanoyloxy, benzoyloxy, Cx-C6 alkylthio, benzyl- thio, benzyloxy, a heterocyclicthio group wherein the heterocycle is a 5- or 6-membered heterocyclic ring containing from 1 to 4 ring nitrogen atoms and/or oxygen or sulfur ring atoms, and wherein 20 the heterocyclic ring is bonded to the thio group via a ring carbon atom; R3 is hydrogen, or Ci-C3 alkyl; and A is a carboxy-protecting group; is reacted in an inert solvent with a free radical 25 initiator to form a l-carba(dethia)cephem or cepham ester represented by formula 2 COOA 240 1 4 5 X-7280 -4- wherein R, Ri , R3 , A and Z have the same meanings as defined above.

The free radical process of that invention can be effected at a temperature between about 45°C and 5 about 150°C, and preferably at between about 60°C and about 90°C. The process is best carried out in an inert solvent which can be a common organic solvent or a mixture of such solvents. For example, solvents such as ethers, alcohols, nitriles, ketones, amides and 10 esters in which the cephalosporin sulfone 1 is at least partially soluble can be used in the process. Examples of solvents which can be used are dipropyl ether, dibutyl ether, diglyme, dioxane, ethanol, propanol, butanol, ethylene glycol, acetonitrile, butyronitrile, 15 benzonitrile, diethyl ketone, methylisobutyl ketone, cyclohexanone, dimethylformamide, dimethylacetamide, hexamethylphosphoramide, ethyl acetate, methyl propionate, ethyl butyrate and methyl benzoate.

Solvents which are known free radical scavengers or 20 trapping agents such as nitrobenzene are to be avoided in the process.

The group Y of the cephalosporin sulfone 1 is defined herein as a "free radical precursor group".

Such groups are those recognized in free radical 25 chemistry as groups which readily provide a free radical upon interaction with free radical-generating conditions. In the context of the invention, the group Y is any group affording the free radical of formula A o COOA provided by the present invention. 24 0 14 5 X-7280 -5- While a number of such groups are known, specific examples are selenides, R4Se- or sulfides R«S-, wherein R4 is Ci-Ca alkyl, C3-C8 cycloalkyl, C2-C6 alkenyl, C2-C6 alkinyl, phenyl, naphthyl, 5 pyrimidinyl, tetrazolyl, pyridinyl, benzothienyl or benzofuryl; a carboxy group; a thiocarbonate, Ar0C(S)0, • ArS-C(S)0, wherein Ar is phenyl or naphthyl; or a heterocyclic thione ester, e.g., (N-pyridyl-2-thione)-oxycarbonyl and (N-pyrimidyl-2-thione)oxycarbonyl. Y 10 also can be a cobalt I salophen such as one formed with cobaltous ion and dibenzalethylene diamine via coordinate covalent bonding and wherein the cobalt is bonded to the 2-methylene group of 1. the free radical A is generated with the Co I salophen and radiation, 15 e.g., UV radiation. A preferred free radical precursor group of this invention is a selenide, R4Se, in particular, an aryl selenide, e.g., phenylselenide wherein Y is C6HsSe-.

Free radical initiators employed in the 20 process can be radiation such as ultraviolet radiation produced, for example, by a mercury-vapor lamp or the like; a peroxide such as dibenzoyl peroxide, an organo-tin hydride such as a tri(Cj-C4 alkyl)tin hydride, a triaryltin hydride, (Ar)3SnH, wherein Ar is phenyl, 25 Cx-C4 alkylphenyl, chlorophenyl, a triaralkyltin hydride such as tribenzyltin hydride and substituted tribenzyltin hydrides, e.g., tri-(4-methylbenzyl)tin hydride, and like organo tin hydrides; a trialkyl-germane, e.g., triethylgermane, or a triarylgermane 30 such as triphenylgermane. The preferred free radical 240 1 X-7280 -6- initiators of the invention are the organo tin hydrides, in particular, trialkyl tin hydrides.

Examples of these preferred tin hydrides are trimethyl-tin hydride, triethyltin hydride and tri-n-butyltin 5 hydride. The organo tin hydride can be used with another free radical initiator, e.g., an azo compound such as 2-21-azobisisobutyronitrile to enhance initiation of the process.

A peroxide initiator can initiate the free 10 radical process with heat, while radiation will directly initiate the process.

The process of the invention proceeds rapidly and converts a cephalosporin (in the form of the sulfone) to the corresponding 1-carba(dethia)cephalosporin. 15 The overall course of the free radical reaction involved in the process is illustrated by the following reaction scheme.

X-7280 * 3 % 240 14 5 * H °\\ f ,s.

/ R, H -C —Y I COOA Free radical generator O O Ri H .Rj : = hc>_ tt N> y—.. : B COOA COOA 2<+o«fS As is shown above, the key radical B as provided by the invention in New Zealand Patent Specification No. 240144 is formed by intramolecular radical transfer of A with loss of S02• Collapse of radical B to radical C is followed by termination of the process with a hydrogen atom. The "~v' 5 terminating hydrogen can be provided by the tin hydride employed in the process or from another source, e.g., the solvent.

The product 2 obtained in the process is recovered from the reaction mixture by conventional 10 procedures and is separated from side products and purified by chromatography. When the starting material 1 is a 3-cephem (Z = ). the l-carba-3-cephem product 2 is accompanied by some isomeric l-carba-2-cephem (Z = ) • The isomer can be readily isomerized to the desired 3-cephem by treatment with a tertiary amine such as triethylamine. A side product frequently observed in the process wherein an organo tin hydride is employed is the 2,3-dimethyl-3-methyl-3-cephem sulfone ester. The latter side product is 20 apparently formed via a 2-electron reduction rather than by a free radical course.

Free radical A is a transient intermediate the existence of which is demonstrated not only by the product obtained via its O generation as shown in the above reaction scheme but also by free radical trapping experiments. For example when the compound 1 is reacted under the process conditions described above to 30 generate radical A, except that 10% nitrobenzene is 2 0 DEciypj 240145 X-7280 -9- added to the reaction mixture, the radical A is trapped and reduction products are formed via a 2-electron process instead of the described products resulting from the free radical course. The existence of this 5 radical also may be demonstrated by physical methods.

Preferred radical compounds of this invention are represented by formula a when R is acylamino, particularly phenyl acetyl amino and phenoxyacetylamino; R3 is hydrogen; and A is t-butyl, allyl or benzyl. An example of such a preferred radical is The starting material 1 can be a 7-acylamino substituted cephalosporin sulfone as defined for formula 1. Examples of such groups are those derived from carboxylic acids, in particular, the acyl groups found 24014 5 -7280 -10- in the 7-position of cephalosporin and the 6-position of penicillin antibiotics. In particular, the acyl group R4CO- of the acylamino group R4CONH, is C!-C5 alkanoyl, substituted C2-C5 alkanoyl substituted by halogen, cyano 5 or hydroxy; an arylacetyl or heteroarylacetyl group represented by the formula 0 II R°-CH-C- I Q in which R° is thienyl, benzothienyl, furyl, benzofuryl, thiazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyrazolyl, thiadiazolyl, oxadiazolyl, pyridyl, or these heterocyclic rings substituted by Cj-C4 alkyl, amino, protected amino or hydroxy; cyclo-20 hexadienyl, napththyl, phenyl or a substituted phenyl group represented by the formula in which a and a', independently, are hydrogen, halogen, hydroxy, (^-04 alkyl, C!-C4 alkoxy, amino, 30 aminomethyl, methylsulfonylamino, hydroxymethyl, trifluoromethyl, carboxy, protected carboxy, carboxy-methyl or protected carboxymethyl; Q is hydrogen, 240149 X-7280 -11- hydroxy, C1-C4 alkanoyloxy, carboxy, protected carboxy, sulfo(-SO3H), amino, protected amino, or a substituted amino group represented by the formula H O x O I || I || -N-C-N-C-R' in which R' is furyl, thienyl, phenyl, halophenyl, methylphenyl, styryl, halostyryl, methylstyryl; or a 10 group of the formula y I -N-R» ' in which R* ' is hydrogen, Cl-CA alkyl, benzyl, C2-Cs alkanoyl or C!-C3 alkylsulfonyl; and x and y, when taken separately, are hydrogen or C1-C4 alkyl, and when taken together form a 5- or 6-membered ring represented by the formula 20 O II C / \ -N N-R'' ( ) <CH2)g in which R' ' has the same meanings as defined earlier and q is 2 or 3; or 30 Q is a substituted amino group of the formula o o H H (Ct-C4-«|k)-N N—C N- w 240145 X-7280 -12- or Q is a benzamido group represented by the formula ,HO*;Q_U_ in which b' is an integer of from 1-3; or R4CO is an acyl group of the formula in which a and a' have the same meanings as defined earlier, Z is 0 or S, and n is 0 or 1; or an oximino-substituted acyl group of the formula O II R°-C-C- II N \ O-R''' in which R° is as defined earlier, and R1'' is hydrogen, Cx-C4 alkyl, or a carboxy-substituted alkyl or cycloalkyl group of the formula 240 1 X-7280 -13- © o -C-(CH2) COOR!»1» i m in which m is 0-3, and c and d when taken separately are, independently, hydrogen or C^-Cs alkyl, and when 10 taken together with the carbon atom to which they are bonded form a 3- to 6-membered carbocyclic ring; and wherein R'11' is hydrogen, Ci-C4 alkyl, or a carboxy-protecting ester-forming group.

Examples of the acyl groups defined above 15 when R is an acylamino group are acetyl, propionyl, cyanoacetyl, bromoacetyl, phenylacetyl, phenoxyacetyl, phenylthioacetyl, benzoyl, thienylacetyl, furylacetyl, benzothienylacetyl, benzofurylacetyl, phenylglycyl, mandeloyl, phenylmalonyl, o-sulfophenylacetyl, cr-(4-20 hydroxybenzamido)phenylacetyl, a -(4-ethylpyrazin-2,3-dione-l-ylcarbonylamino)-a-phenylacetyl, 4-chloro-phenylthioacetyl, 4-hydroxyphenylglycyl, 2, 6-dimethoxy-benzoyl, 3-chloro-4-hydroxyphenylglycyl, 2-(2-amino-thiazol-4-yl)-2-methoxyiminoacetyl, and 2-(2-amino-25 thiazol-4-yl)-2-carboxymethoxyiminoacetyl.

Preferred acyl groups of this invention are phenylacetyl and phenoxyacetyl.

Protected amino groups represented by R are those conventional protecting or blocking groups 30 commonly employed for the temporary protection of an amino group. Such groups are frequently used during the preparation of a compound to prevent unwanted side 240 1 X-7280 -14- reactions involving an unprotected amino group. For example, an amino group is protected or blocked when it might compete with an acylation reaction or esterifica-tion reagent directed at another site in the same 5 molecule. Examples of such conventional protection groups are the aryl, aralkyl, alkyl, cycloalkyl or bicyclo-oxycarbonyl groups 0 . II R -O-C- wherein R5 is aryl e.g. phenyl, 4-methylphenyl, or naphthyl; aralkyl e.g. benzyl or 4-methoxybenzyl; alkyl e.g. C!-C4 alkyl such as methyl, ethyl or t-butyl; 15 cycloalkyl e.g. cyclopropyl, cyclopentyl or cyclohexyl; bicycloalkyl e.g. adamantyl or bicycloheptenyl, and the like. The amino protecting group can also be an enamine such as is formed with the free amino group and a p-keto ester or p-diketone such as for example, ethyl aceto-20 acetate, methyl acetoacetate, acetylacetone or benzoyl-acetone and the like. Other conventional protecting groups which can be represented by R include triphenyl-methylamino, diphenylmethylamino, the "Ox" group wherein R is 4,5-diphenyl-4-oxazolin-2-one-l-yl, or the halo-25 acetyl groups e.g. chloroacetyl or dichloroacetyl.

Carboxy protecting groups represented by A in the formula 1 are conventional protecting groups commonly used in the p-lactam art for the temporary protection or blocking of the acidic carboxy group to 30 prevent its competition with desired reactions carried out at other sites in the molecule. Examples of such 240145 X-7280 -15- protecting groups are alkyl, alkenyl, haloalkyl, aralkyl, silyl, active esters formed with N-hydroxy compounds anhydrides, and the like. Examples of such groups are alkyl such as ethyl, t-butyl or t-amyl; alkenyl such as allyl, 2-butenyl or 2,2-dimethylpropenyl; aralkyl such as benzyl or substituted benzyl e.g. 4-methoxybenzyl or diphenylmethyl; silyl groups such as tri(C!-C4 alkyl)silyl such as trimethylsilyl, triethyl-silyl, t-butyl-dimethylsilyl or 2-(trimethylsilyl)ethyl; 10 active esters formed with N-hydroxy compounds such as phthalimido, succinimido or benztriazole; anhydrides formed by reacting the carboxy groups with a haloformate e.g. anhydrides formed with ethyl chloroformate, methyl chloroformate or isobutyl chloroformate; anhydrides 15 formed with other acids such as acetic acid or benzoic acid; active esters formed with phenols such as penta-chlorophenol; and other conventional carboxy protecting groups such as phenacyl or chlorophenacyl.

With reference to the term R2 of formula I 20 "Cj-C6 alkyl" refers to the straight and branched chain alkyl groups such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, t-butyl, n-pentyl, neopentyl, n-hexyl and the like; "C2-C6 alkenyl" refers to vinyl, allyl, 2-butenyl, 3-pentenyl and the like; 25 "halogen" refers to fluoro, chloro, bromo, and iodo, "Cj-C4 alkoxy" refers to methoxy, ethoxy, propoxy, t-butoxy, n-butoxy and the like "C1-C4 alkylthio" refers to methylthio, ethylthio, propylthio, n-butylthio and the like; "tri(C1-C4 alkyl)silyl" 30 refers to trimethylsilyl, triethylsilyl, tri-(n- X-7280 240 14 5 butyl)silyl, t-butyldimethylsilyl, and like groups; "C2-C6 alkanoyloxy" refers to acetcxy, propionoxy, butyryloxv and the like; and "Cj-C^ alkylsulfonyloxy" refers to methylsulfonvloxy, ethylsulfonyloxy, n-butyl-5 sulfinyloxy and the like. by R2' refers to the 5- and 6-membered heterocyclic rings having a sulfur atom bonded to a ring carbon atom ~ of the heterocycle. Examples of such groups are 10 provided hereinafter and are named arbitrarily for convenience by naming the heterocycle and indicating the location of the bonding of the thio -S-group to the ring, e.g. pvrrol-2-thio refers to the group pyridin-2-thio, pyridin-3-thio, pyridin-4-thio, imidazol-2-thio, pyrazin-2-thio, pvrimidin-2-thio, s-triazin-2-thio, as-triazin-5-thio, thienyl-2-thio, 20 furyl-2-thio, pyran-2-thio, thiopyran-2-thio; triazolyl-2-thio, oxazolyl-2-thio; 1,3,4-oxadiazolyl-2-thio, 1,3,4-thiadiazolyl-2-thio, tetrazolyl-2-thio, and like 5- and 6-membered heterocyclicthio groups. by formula I, wherein Y is R«Se- or R4S-, are obtained by the reaction of a 2-methylene sulfone represented by the formula 3 below.

The term "heterocyclicthio" group represented H The 2-substituted-methylsulfones represented 3 COOA 240 14 5 X-7280 -17- with the selenol compound R4SeH or mercaptan R4SH wherein R4 has the same meanings as defined hereinabove. For example, selenophenol can be reacted with 3 to provide the 2-phenylselenomethy 1 sulfone 1.

The reaction of the mercaptan or selenol compound can be carried out as described by Wright et al. U.S. r> Patent No. 3,660,395 by substituting a cephalosporin sulfone for the cephalosporin sulfoxide employed by Wright et al. Any of the 2-thiosubstituted methyl 10 cephalsoporin compounds described by Wright et al. can be employed in the sulfone form as starting materials in the process of the invention.

The 2-exomethylene sulfones (3) are prepared via a Mannich-type reaction of a 2-unsubstituted 15 cephalosporin sulfone. For example, a 7-acylamino- 3-methyl-3-cephem-4-carboyxlic acid ester sulfone can be reacted with the aldehyde R3C(0)H and a secondary amine hydrochloride such as dimethylammonium chloride to provide an unstabile dimethylaminomethy1 adduct. The 20 unstabile adduct decomposes to form the 2-exomethylene cephem sulfone (3). This method for preparing (3) is described by Wright, U.S. Patent No. 3,660,396 wherein cephalosporin in the sulfoxide form are converted to 2-exomethylene sulfoxides. Substitution of 25 cephalosporin sulfones for the sulfoxide form used by Wright provides 3.

Examples of aldehydes R3C(0)H are formaldehyde, acetaldehyde and propionaldehyde.

The starting material (1) wherein Y is a 30 carboxy group can be prepared with the known 2-carboxy O r 240 X-7280 -18- cephalosporin. A 2-carboxy cephalosporin ester is first oxidized to the sulfone with excess per acid e.g. m-chloroperbenzoic acid, persulfuric acid, or with permanganate. The 2-carboxy cephalsoporin sulfone is 5 then converted to the acid chloride which on reaction with diazomethane proceeds via the Amdt-Eistert reaction to provide the 2-carboxymethyl cephalosporin sulfones (1).

Examples of cephalosporin sulfones (1) which 10 can be used in the process of the invention of New Zealand Patent Specification No. 230640 are shown below in Table 1. % 240 14 5 X-7280 -19- TABLE 1 2-Substituted-Methyl Cephalosporin Sulfones of Formula 1 Z =^Lr2> ^-^2 R 52 *a Y a 1 C6H5CH2C(0)NH- H -ch3 H C6H5Se- allyl 2 C6H50CH2C(0)NH- H -ci H C6H5Se- allyl 3 C6H50CH2C(0)NH- •och3 H H c6h5-s- pMB1 4 C6H50CH2C(0)NH- H -ch=ch2 H CU3Se- -ch3 C6HsCH(NH2)C(0)NH- H -ci H n-C4H9Se- TCE2 6 2-Thienylacetylamino H -sch3 h -cooh allyl 7 t-C4H90C(0)NH- h -och3 -ch3 C6Hs-S- pMB 8 t-C4H90C(0)NH- H ch2r2* h c6h5-s- pMB 9 CH3C(0)NH- h -CH20C(0)CH3 h C2HsSe- t-C4H9 c6h5oc(o)nh- h -CH20C(0)CH3 Pyrimidin-2- Se z = ^lch2 11 C6HsC(0)NH- H - -ch3 n-C4H9Se- DPM3 12 C6Hs-CH2C(0)NH- H - H C6H5Se- DPM 13 2-thienylacetylamino > H - H pyridinyl-2- Se- allyl 14 2-aminothiazole-4-yl-2-methoxyimino-acetylamino H H C6Hs-3- C6HSCH2 240 14 5 X-7280 c6h5och2c(o)nh- h 16 2-furylacetylamino H 17 t-CH4H90C(0)NH- H H 5-tetra2olyl-Se- C6HsCH2-H C6H5-S- C6HsCH2- C2Hs C6H5-Se- allyl n 1/pMB = p-methoxybenzyl 2/TCE = 2,2,2-trichloroethyl 3/DPM = diphenylmethyl A preferred embodiment of the process 10 described therein comprises the use of a compound of the formula 1 wherein Y is the group R4Se-, R3 is hydrogen, 2 is R2 wherein R2 is chloro, methyl or hydrogen, R: is hydrogen, R is an amino-protected phenylglycylamino group, A is allyl, benzyl, diphenylmethyl, or t-butyl, 15 and the free radical initiator is tri(n-butyl)tin hydride.

Another preferred embodiment of the process O comprises use of the compound (1) wherein R is phenoxyacetylamino or phenylacetylamino, Rt is hydrogen, 20 Z is = CH2, R3 is hydrogen, Y is C6H5Se-, and A is allyl.

A further preferred embodiment of the process 'jjl comprises the use of a compound of formula 1 wherein R is phenoxyacetylamino, phenylacetylamino or an amino-protecting group, ra and r3 are hydrogen, Z is ;s^i-r2 wherein r2 is methyl, hydrogen or chloro. 240 1 4 5 X-7280 -21- The following Examples are provided to m further describe the invention and are not to be considered as limiting thereof.

Preparation 1 Preparation of allyl 70-phenoxyacetylamino-2-exomethyl- WW ene-3-methyl-3-cephem-4-carboxylate 1,1-dioxide A slurry of 42.85 g (200 mmole) of 7-amino- deacetoxycephalosporanic acid (7-ADCA) in 400 ml of dioxane and 200 ml of water was treated with 200 ml of IN sodium hydroxide over 30 minutes. A solution of 29 ml (210 mmole) of phenoxyacetyl chloride in 130 ml of 15 acetone and 100 ml of 2N sodium hydroxide were separately and simultaneousl added via dropwise addition at a rate such as to maintain the pH of the slurry at pH 8-9. The solution obtained was evaporated under vacuum to remove volatiles and extracted with 20 diethyl ether to remove any neutral material.

The solution of sodium 7-phenoxyacetylamino-3-methyl-3-cephem-4-carboxylate was added to a solution of 71.3 g (210 mmole) of tetra-n-butylammonium hydroxide sulfate in 700 ml of methylene chloride and 25 700 ml of water which had been readjusted to pH 7.5 with 2N sodium hydroxide. The mixture was stirred for about 5 minutes and the methylene chloride layer was separated. The aqueous phase was extracted twice with methylene chloride and the extracts were combined with the organic 30 layer. The organic layer was dried over magnesium sulfate and evaporated to a brown oil. The oil was 0 240 1 4 5 X-7280 -22- dissolved in 250 ml of chloroform and 34.6 ml (400 mmole) of allyl bromide (previously filtered through activated alumina) were added with stirring. The mixture was stirred for about 19 hours at room 5 temperature and when thin layer chromatography indicated some remaining starting material, 17 ml of allyl bromide were added and the mixture was heated to 50°C with stirring for about 2 hours. The reaction mixture was evaporated on a rotary evaporator to remove 10 chloroform and the concentrate was dissolved in 3:1, v:v of diethyl ether:methylene chloride and the solution extracted twice with pH 7 buffer, once with brine and was dried over magnesium sulfate. The solution was evaporated under vacuum to provide allyl 7-15 phenoxyacetylamino-3-methyl-3-cephem-4-carboxylate as a crude yellow solid.

The crude ester (ca. 200 mmole) was dissolved in 800 ml of DMF, the solution was cooled to 5°C, and a solution of 43.9 g (210 mmole) of m-chloroperbenzoic 20 acid (85% tech.) in 250 ml of ethyl acetate was added at a rate such that the temperature was maintained below 25°C. After the addition was complete, thin layer chromatography showed mostly sulfoxide plus a trace of sulfone but no starting material. The mixture 25 was then warmed to room temperature to provide a mixture of sulfoxide and sulfone. This mixture was combined with another preparation of the sulfone carried out as follows: A solution of 24 g (59.3 mmole) of allyl 7-30 phenoxyacetylamino-3-methyl-3-cephem-4-carboxylate 240 14 5 X-7280 -23- 1-oxide in 200 ml of DMF was treated at room temperature with 13.6 g (65 mmole) of m-chloroperbenzoic acid. The reaction mixture was poured into ethyl acetate and the solution extracted three times with 1:1 NHC1 5 chloride:brine, once with pH 7 buffer, once with bicarbonate, and was dried and evaporated to dryness. The residue was combined with the sulfoxide-sulfone mixture obtained as described above and the sulfone crystallized from di-isopropyl ether-methylene 10 chloride. The mother liquor was chromatographed via preparative HPLC to provide more sulfone product. The combined weight of sulfone obtained was 43.0 g.

To a solution of 43.0 g (102.2 mmole) of the sulfone, allyl 70-phenoxyacetylamino-3-methyl-3-cephem-15 4-carboxylate, 1,1-dioxide, in 600 ml of dioxane were added 150 ml of 3 7% aqueous formaldehyde. The solution was stirred at room temperature and 12.64 g (155 mmole) of dimethylammonium chloride were added. The mixture was stirred at room temperature for about 2 hours and 20 after removal of about half of the dioxane by evaporation under vacuum, a solid formed. The whole mixture including the solid was partitioned between ethyl acetate and 1:1, brine:IN HCl. The ethyl acetate layer was separated, dried over magnesium sulfate and 25 evaporated to dryness on a rotary evaporator. The solid residue of product was crystallized from di-isopropyl ether-methylene chloride. There were obtained 40.3 g (91%) of the desired product, allyl 7p-phenoxyacetylamino-2-exomethylene-3-methyl-3-cephem-4-30 carboxylate, 1,1-dioxide. 40145 X-7280 -24- Mass Spectrum (field desorption): M* 432 UV Spectrum (C2H5OH) \ max 307 nm e = 4092 A max 261 nm e = 7558 IR Spectrum (KBr): 1772 cm'1 (p-lactam carbonyl) 5 1732 cm"1 (ester carbonyl) NMR: (CDC13) 6 2.23 (s, 3H), 4.59 (s, 2H), 4.80 (d, 2H), 4.91 (d, 1H), 5.35 (d, 1H), 5.39 (d, 1H), 5.95 (m, 1H), 6.20 (d, 1H), 6.25 (d/d, 1H), 6.65 (d, 1H), 6.90-7.38 (aromatic H), 8.02 (d, 1H).

Preparation 2 © Allyl 70-phenoxyacetylamino-2-phenylselenomethyl-3-methyl-4-carboxylate, 1,1-dioxide To a solution of 1.30 g (3 mmole) of the 2-methylene sulfone, prepared as described by Preparation 1, in 10.5 ml of acetonitrile was added an excess of selenophenol and the solution was stirred at 20 room temperature for about 30 minutes. The product precipitated from the reaction mixture and was filtered and dried under vacuum. There were obtained 446 mg of the title compound as colorless crystals. The filtrate was evaporated to dryness and the residue of product 25 crystallized from methylene chloride - di-isopropyl ether to provide a second crop.

Mass Spectrum (field desorption): M+ 590 UV (C2H5OH): A. max 239 nm e = 13481.6 NMR: (CDCI3) 6 2.03 (S, 3H), 3.40 (d, 2H), 3.95 30 (t, 1H), 4.59 (s, 2H), 4.69-4.81 (m, 3H), 5.32 (d/d, 240 14 5 X-7280 -25- 1H), 5.38 (d/d, 1H), 5.85-6.00 (m, 1H), 6.19 (d/d, 1H), 6.90-7.62 (aromatic H), 8.10 (d, 1H).

IR (KBr): 1766 cm"1 (p-lactam carbonyl) 1727 cm"1 (ester carbonyl) Example 1 Allyl 7p-phenoxyacetylamino-3-methyl-l-carba(dethia)-3-cephem-4-carboxy1ate To a suspension of 5 g (8.5 mmole) of allyl 7p-phenoxyacetylamino-2-phenylselenomethy1-3-methyl-3-cephem-4-carboxylate 1,1-dioxide and 2.62 g (16 mmole) of azobisisobutylronitrile in 100 ml of diglyme were 15 added 6.77 ml (25.7 mmole) of tri-n-butyltin hydride. The reaction mixture was heated to a temperature of about 100°C. Gas began evolving from the reaction mixture at a temperature of about 86°C and subsided after about 15 minutes. The maximum temperature reached 20 112°C.

After 25 min. a thin layer chromatogram was run on a small aliquot of the mixture using ethyl acetate:methylene chloride, 15:85, v:v. The chromato-gram showed that all of the starting material had 25 reacted.

The reaction mixture was then evaporated to remove the diglyme and the residue was dissolved in acetonitrile. The solution was washed with pentane and evaporated to dryness to yield 8.9 g of a yellow oil. 30 The oil was chromatographed on Florisil, eluting first 240 1 X-7280 -26- with methylene chloride, next with ethyl acetate: methylene chloride, 20:80, v:v, and then with ethyl acetate. Multiple fractions were collected. The early fractions provided 1.12 g of allyl 70-phenoxyacetyl-5 amino-2-(tri-n-butyltin)methyl-3-methyl-3-cephem-4-carboxylate 1,1-dioxide. The middle fractions r~~~ contained 1.66 g of unidentified reduction products, while the end fractions afforded 0.93 g of a mixture of the l-carba-3-cephem and reduction products. The 10 mixture showed 3 spots on thin layer chromatography on silica gel using ethyl acetateihexane, 60:40, v:v.

The mixture of l-carba-3-cephem and reduction products was chromatographed over silica gel using a gradient of 0 to 60% ethyl acetate in hexane to provide 15 A), 19 mg of the l-carba-3-cephem; B), 510 mg of a mixture; and C), 73 mg of the slower spot on the thin layer.

The l-carba-3-cephem A) allyl 7P-phenoxyacetyl amino- 3 -me thy 1 - 1 -carba ( de thi a ) -3 -cephem-4-20 carboxylate had a molecular weight of 370 as determined by mass spectrum and the following spectral properties.

UV (C2H5OH): A 268; e = 8,584 NMR (CDC13): 6 1.42 (m, 1H), 1.91 (m, 1H), 2.05 (s, 3H), 2.31 (m, 2H), 3.85 (m, 1H), 4.55 (s, 2H), 25 4.65-4.80 (m, 4H), 5.95 (m, 1H), 6.85-7.30 (aromatic H).

The mixture B), 510 mg, was chromatographed over silica gel via gradient elution to provide 49 mg of allyl 7p-phenoxyacetylamino-3-methyl-l-carba(dethia)-2-cephem-4-carboxylate. 240145 X-7280 -27- Mass Spectrum: 370=rT NMR (CDCI3): 6 1.80 (s, 2H), 2.40 (m, 1H), 2.62 (m, 1H), 3.80 (t, 1H), 4.55 (s, 2H), 4.82 (d, 1H), 5.30 (d, 1H) 5.40 (d, 1H), 5.70 (s, 1H), 5.95 (m, 1H), 5 6.90-7.42 (aromatic H).

UV (C2H5OH): \ 268; £ = 12970 \ 275; £ = 2430 The l-carba-3-cephem (A) has the structural formula H H ■OCHjCONH^r J-H.

-CHi COOCH,CHaCHj and the l-carba-2-cephem obtained from mixture B has the formula n 240 1 4 9

Claims (4)

1. WHAT WE CLAIM IS: 9 15 25 l. The free radical compound of the formula A (■). Rw r S JI R-3 CH • o COOA 10 wherein R is amino, acylamino, protected amino, or Cj-C., alkylsulfonylamino; Rx is hydrogen or C2-C4 alkoxy; R3 is hydrogen or C!-C3 alkyl; Z is a divalent group of the formulae JU or J=CH? wherein R2 is hydrogen, C^Ce alkyl, C2-C6 alkenyl, halogen, C!-C4 alkoxy, Cj-C^ alkylthio, tri-(Ci-C4 20 alkyl)silyloxy, C2-Ce alkanoyloxy, Ca-C4 alkylsulfonyl-oxy, trifluoromethylsulfonyloxy, or a substituted methyl group of the formula 12 «2 wherein R21 is hydroxy, Cj-Ce alkoxy, C!-C6 alkanoyloxy, benzoyloxy, Ci~C6 alkylthio, benzylthio, benzyloxy, a heterocyclicthio group wherein the heterocycle is a 5-or 6-membered ring containing from 1 to 4 ring nitrogen 30 atoms and sulfur or oxygen atoms, or sulfur or oxygen atoms and wherein said heterocycle is bonded to the thio group via a ring carbon atom of said heterocycle; and A is a carboxy-protecting group.
2. 2- The compound of claim 1 wherein R is phenylglycylamino, an amino-protected phenylglycyl-5 amino group, phenoxyacetylamino or phenylacetylamino. - 29 - 240 14 5
3. 3. The compound of claim 1 or claim 2 wherein R is ' i phenoxyacetylamino or phenylacetylamino, R3 is hydrogen and A is t-butyl, allyl or benzyl.
4. 4. A free radical compound of the formula A as defined in claim 1 substantially as hereinbefore described with reference to any example thereof. CK,~ 8r l.i juthorised Agent HARK & SON Per: r 1 Li.' 1 ——