CA1060441A - Anti-allergic n-(5-tetrazolyl)-1-oxo-1h-6-alkox-ypyrimido (1,2-a)-quinoline-2-carboxamides and intermediates therefor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A novel series of N-(5-tetrazolyl)-1-oxo-1H-6-alkoxy-pyrimido[1,2-a]-quinoline-2-carboxamides of the formula

Description

This invention relates to N-(S-tetrazolyl)-pyrimido~1,2-a]quinoline-

2-carboxamides and derivatives thereof and to their use as antiallergy agents.
More particularly, it relates to N-tetrazolyl-l-oxo-lH-6-(R3-substituted)-pyrimido[l,2-a~quinoline-2-carboxamides wherein the 6-substituent is chloro, S bromo or lower alkoxy; pharmaceutically-acceptable ca*ionic salts thereof; and derivatives of such compounds wherein the benzenoid ring bears one or more sub-stituents, which are useful as agents for the treatment of allergic reactions, and especially of allergic bronchial asthma; a~d intermediates therefor.

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Allergic reactions, the symptoms resulting from an anti~en-Pntibody intera~ction, manifest themselves in a wide variety~of ways and in dif-erent organs and tissues. Common allergic disorders, for example, are allergic rhinitis, a condition characterized by seasonal or perennial sneezing, running nose, nasal congestion, with itching and congestion of eyes; hay fever, a variety of allergic rhinitis that results from hypersensitivity to grass pol-lens; and bronchial asthma, one of the most disabling and debilitating of l allergic reactions, a disease characterized by hyper-reactivity of the bronchi `
j on exposure to various immunogenic or nonimmunogenic stimuli, resulting in . ~ bronchospasms with wheez~ng, short-lived paroxysms and widespread constriction of airway passages. The mechanical obstruction to airflow in airways is gener-ally reversed by the use of bronchodilators, which provide symptomatic relief.
In contrast, antiallergy agents prevent the release of mediators of anaphylaxis, ¦ rom ti~ue stores, thereby acting in a prophylactic manner to preclude elici-I tation of bronchoconfitriction by the mediators.
f ¦ Efforts to discover medicinal agents to alleviate the symptoms of the abnormal physiologic state have been extensive. As early as 1910, Mat~hews~
¦ Brit. Med. J., 1, 441 (1910) reported the bronchodilator effects of epinephrine.
Since then, Chen and Schmidt, J. Pharmacol. Exper. Therap., 24, 339 (1924 ;;~; reported the use of the alkaloid ephedrine as an orally efficacious broncho-dilator wlth the same spectrum of activity as epinephrine. In 1940, Kon~ett, Arch. ~ . Path. Pharmak., 197, 27 (1940) outlined the effects of the potent aerosol bronchodilator isoproterenol. Cullum et al., Brit. J. Pharmacol. Ex ."
; 25 35, 141 (1969) reported the pharmacology of salbutamol, a potent bronchodilator of prolonged duration, and active via both oral and aerosol administration.
~ ; ~any bronchodilator preparations contain theophylline. These are generally i less potent than the sympathomimetic amines such as isoproterenol and salbuta-~ ~ol, and are in ffectlve Ln aerosol ad=ini~tration. I

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Recen'ly, Cox and co-workers, Adv. in Drug Res., ~ 115 ~1970), des-cribed the pharmacology of one such agent, disodium cromoglycate [1,3-bis(2-carboxycromon-5-yloxy)~2-hydroxypropane, Intal,l~Intall~ is a trademarkO It is not a bronchodilator, but mediates its therapeutic effects by a unique mechan-ism of action involving inhibition of release of mediators of anaphylaxis andis administered prophylactically. It suffers from lack of oral efficacy and, for optimum results, is administered by inhalation as a solid inhalant. Further, although it is effective against anaphylaxis due to immunog~ubulin E ~IgE), it is effective against anaphylaxis due to immunoglobulin G ~IgE) only at high doses C60-70% protection at 100 and 300 mg./kg.).
Although the aforementioned agents represent outstanding contribu-tions toward the treatment of asthma, many of them exert the undesired side effect of cardiac stimulation.
The synthesis of a lH-pyrimido~1,2-a]quinoline appears to have first been reported by Antaki et al., J. Chem. Soc., pages 551-555 ~1951), who con-densed 2-chloroquinoline with ethyl B-amino c~otonate in the presence of anhy-drous potassium carbonate and a trace of copper bronze to produce 1-oxo-lH-3-methylpyrimidoC1,2-a]quinoline. No utility for the compound was reported.
Antaki, J. Am.~Chem. Soc.~ 80, 3066-9 ~1958) reports the condensa-tion of 2-aminoquinoline and ethylethoxymethylenecyanoacetate to give ethyl 2-quinolylaminomethylenecyanoacetate which when distilled under reduced pressure afforded 1-oxo-lH-pyrimido[1,2-a]quinoline-2-carbonitrile. The compound demonstrated antischistosomal action.
Richardson, et al., J. Med. Chem., ~ 1203-6 ¢1972) describe ethyl 1-oxo-lH-pyrimido~1,2-a]quinoline-2-carboxylate and report it to be inactive as an antimicrobial agent. When tested for antiallergy activity by the PCA
test lt was found to exhibit 100% inhibition at 3 mg./kg. by the intravenous (I.V.) route of adm~nistration but is without activity at 1 mg./ke. I.V.

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Approximately 90~ inhibition is demonstrated at 30 mg./kg. by the oral route of administration, but oral activity is absent at a dosage level of lO mg./kg.
via the oral route.
It has now been found that compounds having the formula R ~3 R2~$
N N
0 = ~ - NH~

are valuable antiallergy agents; that is, agents-which inbibit the release of mediators of anaphylaxis, in mammals, including man, and in this way preclude elicitation of bronchoconstriction by the mediators. They are not bronchodila-tors. They are, in contrast to disodium cromoglycate, of practical value against both IgG and IgE mediated anaphylaxis via the oral, intranasal and intraperitoneal routes of administration, and by inhalation. In this formula, each of the benzenoid substituents and Rl and R2 is selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, fluoro and chloro;
Rl and R2 when taken together are alkylenedioxy of 1 to 2 carbon atoms and are selected from the group consisting of methylenedioxy and ethylenedioxy;
R3 is selected from the group consisting of chloro, bromo and lower alkoxy;
and the pharmaceutically-acceptable cationic salts thereof.
The terms "lower alkyl" and "lower alkoxy" as used herein are intend-ed to refer to alkyl and alkoxy groups having from one to five carbon atoms since the reactants necessary to prepare such compounds are more readily , available than are those having larger alkyl or alkoxy groups.

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1~60441 By the term ~pharmaceutically-acceptable cationic saltsl~ is intended salts such as the alkali metal salts, e.g., sodium and potassium; alkaline earth metal salts such as calcium and magnesium; aluminum salts; ammonium salts; and salts with organic bases, e.g., amines such as triethylamine, tri-n-butylamine, piperidine, triethanolamine ? diethylaminoethylamine, N,N'-di-benzylethylenediamine and pyrrolidine.
The 5-substituted tetrazoles, as is known, can exist in two isomeric forms, viz:

N _ ~ ~N _ N
l H
which co-exist in a dynamic tautomeric, equilibrium mixtureO Both forms o~
the tetrazolyl amides are included within the scope of this invention~
The compound6 described herein exhibit a significantly broader spectrum of anti-allergy activity than do the corresponding acids and e6ters.
Their anti-aller W activity is indeed surprising since the corresponding sim-ple amides ~e.g., -CONH2, _coN(c2Hs)2~ are inactive as antiallergy agents when te8ted by the methods do~¢ribed below.
Compounds of particular interest to thi6 in~ention are those wherein R3 is methoxy or ethoxy and the benzenoid variables (Rl, R2) are hydrogen and those wherein R3 is methoxy and at least one of the benzenoid substituents is lower alkoxy Dr ~luoro, the remaining benzenoid substituent being hydrogen.

Rl R2 R3 H H OCH3, OC2H5 H CH3 OcH3~ C2H5 H OC~3 OCH3 ; H F OCH3 "~

`` 1060441 The antiallergy property of the compounds of this invention is evaluated by the passive cutaneous anaphylaxis (PCA) test (Ovary, J. Immun., 81, 355, 1958). In the PCA test, normal animals are injected intradermally (i.d.) with antibodies contained in serum obtained from actively sensitized S animals. The animals are then challenged intravenously with antigen mixed with a dye such as Evans' Blue. The increased capillary permeability caused by the antigen-antibody reaction causes the dye to leak from the site of the antibody injection. The test animals are then asphyxiated and the intensity of the reaction determined by measuring the diameter and intensity of the blue coloration on the inner surface of the animals' skin.
According to the present invention there is provided a process for preparing such N-(5-tetrazolyl)-pyrimido~1,2-a]quinoline-2-carboxamides by dehydrative coupling of the appropriate l-oxo-lH-6-(R3-substituted)pyrimido [1,2-a]-quinoline-2-carboxylic acid with S-aminotetrazole. The dehydrative coùpling is accomplished by means of a wide variety of agents commonly used in peptide synthe~es. Representative agents include N,N'-carbonyldiimidazole, N,N~-carbonyl-di-s-triazine, ethoxyacetylene, l,l-dichlorodiethylether, diphenylketene p-tolylimine, N-hydroxyphthalimide, N-hydroxysuccinimide, N-hydroxypiperidine, ethylene chlorophosphite, diethyl ethylene pyrophosphite, N-ethyl-5-phenyliso~azolium-3'-sulfonate, phenylphosphorodi-(l-imidazolate) and carbodiimides such as dicyclohexylcarbodiimide, 1-cyclohexyl-3-(2-morpholino-methyl)carbodiimide, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydro-chloride, l-ethyl-3-(3'-dimethylaminopropyl)carbodiimide hydrochloride and diethyl cyanamide.
The above-described coupling agents are generally reacted first with the acid reacta~t and the resulting product then reacted without isolation with ~::

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5-aminotetrazole to afford the desired N-(5-tetrazolyl)-1-oxo-lH-6-(R3-substituted)pyrimido[l,2-a]quinoline-2-carboxamides. The reaction is carried out in a reaction-inert solvent system in which the acid reactant need not be soluble. The only reqirement for the solvent system is that it not enter into any appreciable reaction with the reactants or products. The variety of coupling agents which can be used to bring about the dehydrative coupling allow a widè choice of solvents. Representative solvents are N,N-dimethyl-formamide, tetrahydrofuran, dioxane, methylene chloride, nitromethane and acetonitrile.
The reaction of the acid reactant with the coupling agent is conduc-ted at a temperature of from about 20C. to about 110C. The reactive intermediate is then reacted with 5-aminotetrazole at from about 20C. to 110C. Each of these steps is advantageously carried out at from about 50C.
to about 100C. since the rate and yield of the reaction are improved.
The molar ratio of acid:coupling agent:5-aminotetrazole is generally about 1:1:1 to about 1:1.1:1.1. Higher ratios of coupling agent and 5-amino-tetra~ole can be used but offer no advantages. Excesses of ten mole percent are satisfactory.
As those skilled in the art will recognize, all reactants can be added at once rather than in stepwise fashion as described above. However, prior formation of the reactive intermediate ~acid-coupling agent product) normally produces better yields of desired N-(5-tetrazolyl)amides.
A favored coupling agent is N,N'-carbonyldiimidazole since it affords a smooth reaction and reasonable yields of desired product without optimiza-tion of reaction conditions. When using this coupling agent, N,N-dimethyl-formamide and a temperature of from 85C. to 100C. are preferred conditions for reasons mentioned above.

.

:106~441 The compounds wherein R3 is alkoxy are also conveniently prepared by the Williamson reaction between the appropriate N-(5-tetrazolyl)-l-oxo-lH-

6-chloro(or bromo)pyrimido[l,2-a]quinoline-2-carboxamide and the appropriate alkanol as exemplified herein.
The required l-oxo-lH-6-(R3-substituted)pyrimido[1,2-a]quinoline-2-carboxylic acids are prepared by condensation of the appropriate 2-amino-4-(R3-substituted)quinoline with the appropriate dialkyl ethoxymethylenemalonate to produce the corresponding intermediate dialkyl 4-(R3-substituted)-2-quinolyl-aminomethylene malonate which is then cyclized to the desired alkyl l-oxo-lH-6-(R3-substituted)pyrimido[1,2-a]quinoline-2-carboxylate.
The condensation is carried out by heating a stoichiometric mixture of the 2-aminoquinoline reactant and the dialkyl ethoxymethylenemalonate at a temperature of from about 80C. to about 125C. Lower temperatures are not desirable because the reaction proceeds at too slow a rate. Higher temperatures lS can be used but appear to offer no advantages. The reaction is thus conveni-ently carried out as a melt. It can, of course, be conducted in a solvent or mixture of solvents; for example, ethanol, N,N-dimethylformamide, acetonitrile.
However, from a practical standpoint a solvent appears unnecessa~y.
The intermediate dialkyl 4-(R3-substituted)-2-quinolylaminomethylene-malonate thus produced is then cyclized, preferably thermally, by heating to a temperature of from about 175C. to about 250C. in a suitable reaction-inert ~ diluent; that i8, in a compound which permits control of the reaction tempera-- ture, i8 stable to the relatively high temperatures employed and which does not react with the starting material or the products of cyclization. Representativeof such diluents are high boiling hydrocarbons such as perhydronapthalene, mineral oil, diethylbenzene, acetic anhydride contai~ing sulfuric acid, dl-phenyl ether and diphenyl, especially that which contains 26.5% diphenyl and 73.5% diphenyl ether and is sold as Dowtherm A ("Dowtherm" is a trademark).

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The alkyl l-oxo-lH-6-(R3-substituted)pyrimido[1,2-a]quinoline-2-carboxylates are converted to the correspond;ng acids by hydrolysis, preferably acid hydrolysis. The usual conditione comprise heating an aqueous mixture of the appropriate ester and a m;neral acid such as hydrochloric, sulfuric, phos-phoric or nitric acids, from about 50C. to about 100C. for periods of up tofour hours or until hydrolysis is essentially complete. The favored mineral acid is hydrochloric acid of from 3N to 12N concentration. The less soluble the ester reactant in water, the more concentrated the acid used for hydrolys;s.
The free acids generally crystallize from the hydrolysis reaction mixture upon cooling and are recovered by filtration. When crystallization does not occur the acids are recovered by evaporation of the reaction mixture. The acids are purified by recrystallization from suitable solvents, such as N,N-dimethyl-formamide.
Salt formation is accomplished by reacting the appropriate acid with the approprlate metal salt~ such as a carbonate, bicarbonate, acetate, hexano-ate, hydroxide, ln suitable medium such as water, methanol or ethanol according to well-known procedures, The salts are recovered by standard methods such as by filtration if they are insoluble in the medium, by evaporation of the sol-vent if they are soluble in the medium or by precipitation by addition of a non-solvent for the salt.
As noted above, the N-(5-tetrazolyl)amides of this invention exhibit a significantly broader spectrum of antiallergy activity than do the precursor acids. The acids are effective in inhibiting only anaphylactic phenomena mediated by immunoglobin E (IgE). In contrast, the N-(5-tetrazolyl)amides are not only effective against reaginic induced anaphylaxis (IgE, immunoglobin E), but also against immunoglobin G (IgG) ;nduced anaphylaxis. This behavior is also in contrast to the action of disodium cromoglycate which does not inhibit IgG-medlated responsçs except at high doses.

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The products of this invention and the pharmaceutically-acceptable cationic salts thereof are useful as prophylactic agents to inhibit or prevent the release of mediators of anaphylaxis (allergy, immediate hypersentitivity reactions) and the occurrence of allergic symptoms in mammals, and can be administered for such uses individually or as mixtures with other agents; for example, with theophylline or sympathomimetic amines. They can be admin;stered alone, but are generally administered with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice. For example, they can be combined with various pharmaceutically acceptable inert carriers in the form of tablets, capsules, lozenges, troches, hard candies, powders, aerosol sprays, aqueous suspensions or solutions, injec-table solutions, elixirs, syrups and the like. Such carriers include solid diluents or fillers, sterile aqueous media and various non-toxic organic sol-vents. Moreover, the oral pharmaceutical compositions of this ;nvention can be suitably sweetened and flavored by means of various agents of the type commonly used for this purpose.
The particular carrier selected and the proportion of active ingredi-ent to carrier are influenced by the solubility and chemical nature of the therapeutic compounds, the chosen route of administration and the needs of standard pharmaceutical practice. For example, when the compounds of this invention are administered orally in tablet form, excipients such as lactose, sodium citrate, calcium carbonate and dicalcium phosphate can be used. Various disintegrants such as starch, alginic acids and certain complex silicates, together with lubricating agents such as magnesium stearate, sodium lauryl sulphate and talc, can also be used in producing tablets for the oral adminis-tration of these compounds. For oral administration in capsule form, lactose and high molecular weight polyethylene glycols are among the preferred materi-als for use as pharmaceutically-acceptable carriers. Where aqueous suspensions -lQ-..

1060~41 are to be used for oral administration, the compounds of this invention can be combined with emulsifying or suspending agents. Diluents such as ethanol, propylene glycol, glycerine and chloroform and their combinations can be employed as well as other materials.
For the purpose of parenteral administration and inhalation, solu-tions or suspensions of these compounds in sesame or peanut oil or aqueous propylene glycol solutions can be employed, as well as sterile aqueous solutionsof the soluble pharmaceutically-acceptable salts described herein. These par-ticular solutions are especially suited for instramuscular and subcutaneous injection purposes should such method of administration be desired. The aqueous solutions, including those of the salts dissolved in pure distilled water, are also useful for intravenous injection purposes provided that their pH is properly adjusted beforehand. Such solutions should also be suitably buffered, if necessary, and the liquid diluent first rendered isotonic with sufficient saline or glucose.
The compounds can be administered to asthmatic subjects suffering from bronchoconst~iction~by means of inhalators or other devices which permit the active compounds to come -into direct contact with the constricted areas of the tissues of the subject. When administered by inhalation, the composit;ons can comprise (1) a solution or suspension of the active ingredient in a liquid medium of the type mentioned above for administration via a nebulizer; (2) a suspension or solution of the active ingredient in a liquid propellant such as dichlorodifluoromethane or chlorotrifluoroethane for administration from a pressurized container; or (3) a mixture of the active ingredient and a solid diluent (e.g., lactose) for administration from a powder inhalation device.
Compositioas suLtable for inhalation by means of a conventional nebulizer will comprise about O.l to about 1% of active ingredient; and those for use in ~ .

" 1060441 pressurized containers will comprise from about 0.5 to about 2% of active in~redient. Compositions for use as powder inhalants can comprise ratios of active ingredient to diluent of from about 1:0.5 to about 1:1.5.
It is necessary that the active ingredient form a proportion of the composition such that a suitable dosage form will be obtained. Obviously, several dosage unit forms can be administered at about the same time. Although compositions with less than 0.005% by weight of active ingredient might be used in certain instances, it is preferred to use compositions containing not less than 0.005% of the active ingredient; otherwise, the amount of carrier becomes excessively large. Activity increases with the concentration of the active ingredient. The CompositiQn may contain 10, 50, 75, 95, or an even higher percentage by weight of the active ingredient.
As regards the dosage regimen of the compounds of this invention, the physician will ultimately determine the dosage which will be most suitable for a particular individual, and it will vary with age, weight and response of the partlcular patient as well as with the nature and extent of the symptoms, the pharmacodynamic characteristics of the particular agent to be administered and the route of administration chosen. Generally, small doses will be administered initially, with a gradual increase in the dosage untiI optimum level is deter-23 mined. It will often be found that when the composition ;s administered oral~
ly, larger quantities of the active ingredient will be required to produce the ~ same level as produced by a small quantity administered parenterally.
; - Having full regard for the foregoing factors, it is considered that an effective daily oral dosage of the compounds of the present invention in humans of from about 10 to about 1500 mg. per day, with a preferred range of :
about 10 to about 6~0 mg. per day in single or divided doses, or at about 0.2 to about 12 mg./kg. of body weight will effectively alleviate bronchoconstric-:, ~
h~ tion in human sub~ects. These values are illustrative and there may, of ; course, be individual cases where higher or lower dose ranges are merited.

~:::: ~ ' , When administered intravenously or by inhalation, the effective daily dose is from about 0.5 to about 400 mg. per day, and preferably from about 0.25 to 200 mg. per day, or at about 0.005 to 4 mg./kg. of body weight in single or divided doses.
The same two basic changes are present in cases of anaphylactic shock: (l) ar increase in permeability of capillaries, and (2) concentration of smooth muscle. The increased capillary permeability is the result of antigen-antibody interaction. It, and smooth muscle contraction, can be observed and readily measured. This increase in capillary permeability forms the basis of the PCA test.
The PCA test is a measure of the anti-allergic (especially anti-asthmatic) activity of a compound. Compounds which inhibit a positive PCA
test induced by the rat immunochemical counterpart of human immunoglobulin E
(IgE), or reagin, are considered to have anti-allergic activity (C. Mota, Ann.
N,Y, Acad. Sci " 103, 264 (1963) ~Reagln is primarily immunoglobulin E [IgE]
and 1s the prin¢ipal immunoglobulin responsible for allergic asthma, anaphy-laxis, hay fever, food sensitivities and certain manifestations of drug sensitivities), Such compounds when administered to a sensitized subject, human or animal, prior tc the time when the subject comes into contact with an$igens or substances to which it is allergic, will prevent the allergic reaction which would ~therwise occur. They, therefore, provide a method for the prophylactic treatment of allergy or anaphylactic reactions of a reagin mediated nature.
;- To put it another way, such compounds block the release of mediators : ~ , ~ 25 resulting from the antigen-an~ibody ~allergic) reaction as illustrated in the ~ - ~
PCA test using rat homocytotropic antibody--a known correlate of human reaginic antibody Inhibition of réaginic antigen-an~ibody reac~ions in rats, the test . ~ ~
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; -13-: ' animal of the PCA test, is regarded as representative of inhibition of human reag;nic antigen-antibody reactions which occur during allergic episodes.
The PCA reaction test procedure employed to evaluate the compounds of the present invention demonstrates an excellent correlation between activity for compounds in this test and their utility in the treatment of allergic asthma. The ability of agents to interfere with PCA reactions is measured in male Charles River Wistar rats, 170-210 g. Reaginic antiserum, rich in IgE
antibodies is prepared according to Petillo et al., Int. Arch. Allergy, 44, 309 (1973). Hyperimmune antiserum rich in IgG antibodies to hen egg albumin is prepared according to Orange, et al., J. Exptl. Med., 127, 767 (1968). Forty-e;ght hours prior to antigen challenge, the reaginic antiserum is injected intradermally (i.d.) into the shaved skin of a normal rat's back; five hours before challenge the hyperimmume antisera is similarly injected. At a third site 60 mcg. histamine dihydrochloride and 0.5 mcg. serotonin creatinine sul-fate are injected i.d. ~ust prior to antigen challenge as a check for anti-histaminic, antiserotonin and unspecific types of blockage; the compounds of the instant invention or saline are then administered i.v. and immediately followed by the challenge of 5 mg. egg albumen and 2.5 mg. Evans's Blue dye in saline. In the case of oral administration Evans's Blue dye and egg albumen are given five minutes after administration of the drug. Thirty minutes later the anim&ls are asphyxiated uslng chloroform and the skin of the back removed and reversed for observation. A score is assigned each in~ection s~te equal to the product of the diameter of the site in mm. and a grade of 0.1, 0.5, 1,2, 3 or 4~proportional to intensity of dye coloration. The scores for a given ; 25 in~ection site are summed for each group of 5 animals and compared to the saline treated controls. The difference i8 expressed as percent blockage due to the compound employ-d.

1060441 - . 1 Comyounds representatiye of those of the prèsent invention are'`
i tested for antiallergy activity by the above-describ~d procedure and the resulting àctivities are reported as the degree (~0~ of protection. Intal, disodium cromoglycate, a commercial a~tiallergy agen~, is included for comparison.
The compounds tested are of the formula `

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~ o o :o o ~ o o ~ o w s --:r: W W :~ W ~ W W

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060441 ;
Example I

~-(5-Tetrazolyl)-l-oxo 1~1-6-me~hoxypyrimido~1,2-a]-_ _______!lUinline-~-carboxamide _ ' A mixture of l-oxo-lH~6-methoxypyrimido~1,2-a~quinoline-2-carboxylic 5acid (540 mg., 2,0 mmole) and N,N'-carbonyldiimidazole (357 mg., 2.2 mmole) in ' N,N-dimethylformamide (15 ml.) is stirred and heated on a steam bath for fif-teen minutes. A clear solution forms after approximately five minutes' heatin~, followed by formation of'a precipitate. The reaction mixture is stirred an additional 45 minutes at ambient temperature and is then treated with 5-amino-tetrazole'(l87 mg., 2.2 mmole). The ~ixture is heated on a steam bath for forty minutes and is then cooled and filtered to recoYer the product (540 mg.
of yellow solid); m.p. 220 C. (dec.).
It is purified by dissolving in hot N,N-dimethylformamide at the rate ' of 200 ~g. crude product per 20 ml. of solvent, fîltering the hot solution and then chilling the filtrate. The yellow crystals are filtered and dried;
m.p. 255 C. (dec.) .
Analysi~: Cslc~d for C15H1103N7: C, 53.41; H, 3.29; N, 29.07 %
~ound: C, 53.12; H, 3.67; N, 28.75 %
The following compounds are similarly prepared from appropriate reactants:

- Rl 13 ' ~ N ~

R2 ~ ~ N~N

O~C~

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o U~
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P~ ~ 0 L'l ~J C~ L''l ~
~D L~~D ~ U~ r~ ~IQ
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-" ` 1061)441 The product of Example VIII ;s purified by dissolution in ammonium hydroxide (6N) from which the product precipitates on standing. The solid is filtered, dissolved in water and precipitated from solution by acidification with 3N hydrochloric acid. It is filtered, dried and recrystallized from N,N-dimethylformamide.
The product of Example IX is purified by recrystallization from N,N-dimethylformamide, followed by the purification method accorded the product of Example VIII.
EXAMPLE X
The compounds tabulated are prepared from appropriate reactants by the procedure of Example I.

Rl O= -N ~ ~ '`~

H

10~0441 t~ a~

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r ~ ~ ~ y~ ~ C'~ 1 O O C) 0~
o~,N 7 ~ ~ ~ ~ ~ $ I I I I ~, ~, $ I q ~ ol ~ 01 ~ ol ol ~

a a-: o o o c~ ~ ~ ~ o o o o o o o U~
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EXAMPLE XI
N-(5-Tetrazolyl)-l-oxo-lH-6-ethoxypyrimido~1,2-a]-quinoline-2-carboxamide A mixture of p-toluenesulfonic acid monohydrate (20 mg.) and N-(5-tetrazolyl)-l-oxo-lH-6-chloropyrimido~1,2-a]quinoline-2-carboxamide (1.79 g.) irl ethanol (75 ml.) is heated at reflux for 24 hours. The solvent is removed under reduced pressure and the residue partitioned between 3N hydrcchloric acid (25 ml.)--ethyl acetate (100 ml.). The phases are separated and the ethyl acetate phase extracted with 3N hydrochloric acid (2 x 20 ml.). The acid ex-tracts are combined, made neutral (pH 7-8) with 20% ammonium hydroxide and the resulting precipitate recovered by ~iltration (235 mg.).
The above procedure is repeated but using the ~-chloro(or bromo) products of Example X and the appropriate a}kanol to give the compounds tabulated below:
Rl R3 O~~
~r H
Rl R2 R3 H 8-OCH3 0-n-C4Hg

7-CH3 lO-OCN3 C2H5 N 10-Cl OCH3 H 8-Cl OCH3 :
H 9-Cl O-n-C3H7

8-OCH3 9-OCH3 OC2H5 EXAMPLE XII
Salt Formation The products of Examples I-XI are converted to the sodium, potassium, ammonium, calciu~, magnesium, aluminum, triethylamine, tri-n-butylamine, piperidine, triethanolamine, diethylamino~thylamine, pyr~oiidine and N,N-di-benzylethylenediamine salts by reaction with an equivalent of the appropriate metal hydroxide, ammonium hydroxide or amine in water or ethanol followed by filtration of the salt if it is insoluble or by evaporation of the solvent if the salt is soluble therein.
EXAMPLE XIII
Injectable Preparation One hundred grams of N-(5-tetrazolyl)-1-oxo-lH-6-methoxypyrimido-~1,2-a]qùinoline-2-carboxamide are intimately mixed and ground with ~50 grams of sodium ascorbate. The ground, dry mixture is placed in vials and steril;zed with ethylene oxide after which the vials are sterilely stoppered. For intra-venous administration, sufficient water s added to the materials in the vials to form a solution containing 5.0 mg. of active ingredient per mill;liter of in~ectable solution.

EXAMPLE XIV
Tablets A tablet base is prepared by blending the following ingredients in the proportion by weight indicated:
5Sucrose, U.S.P. 80.3 Tapioca Starch 13.2 Nagnesium Stearate 6.5 Into this tablet base there is blended sufficient N-t5-tetrazolyl)-l-oxo-lH-6-methoxypyrimido~1,2-a]quinoline-2-carboxamide to provide tablets 10containing 20, 100 and 250 mg. of active ingredient per tablet. The composi-tions are each compressed into tablets, each weighing 360 mg., by conventional means.
EXANPLE XV
Capsules 15A blend is prepared containing the following ingredients:
Calcium carbonate, U.S.P.17.6 Dicalcium pho8phate 18.8 Magnesium trisilicate, U.S.P. 5.2 Lactose, U.S.P. 5.2 Potato starch 5.2 , Magnesium stearate A 0,8 Magnesium stearate B 0,35 To this blend is added sufficient N-t5-tetrazolyl)-1-oxo-lH-6,9-dim-thoxypyrimido[1,2-a]quinoline-2-carboxamide to provide capsules containing 2510, 25, and 50 mg. hard gelatin capeules in the amount of 350 mg. per capsule.

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:, In like manner, capsules containing 2.0 mg. and 6.0 mg. of active ingredient, and having 300 mg. of the following blends per capsule are prepared:
IngredientsWeight mg./capsule Drug 2.00 N-Methylglucamine18.00 Lactose, anhydrous 241.20 Corn starch, anhydrous 30.00 *Talc 8.80 IngredientsWeight mg./capsule Drug 6.00 N-Methylglucamine18.00 Lactose, anhydrous 237.20 Corn starch, anhydrous 30.00 *Talc 8.80 *Talc added before encapsulation EXAMPLE XVI
Solution A solution of N-(5-tetrazolyl)-1-oxo-lN-6-methoxy-9-fluoropyrimido-[1,2-a]quinoline-2-carboxamide i8 prepared with the foIlowing composition:
Effective ingredient 6.04 grams Magnesium chloride hexahydrate 12.36 grams : , ; - Monoethanolamine 8.85 ml.

Propylene glycol 376.00 grams 5 25~ Water, distilled 94.00 ml.

The resultant solution has a concentration of effective ingredient of ,: ~ f -10 mg./ml. and is suitable for parenteral and, especially for intramuscular administration.

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EXAMPLE XVII
An aqueous solution of N-(5-tetrazolyl)-1-oxo-lH-6-methoxypyrimido-[1,2-a]quinoline-2-carboxamide sodium salt (containing 3 mg. of drug per ml. of solution) is placed in a standard nebulizer such as ls ava;lable from the Vaponephrine Co., Edison, N. J. The solution is sprayed under an air pressure of 6 lbs. per square inch into a closed 8" x 8" x 12" plastic container for six minutes. The container has four openings to ~ccommodate-the heads of four rats. Four rats are exposed to the drug simultaneously with only the;r heads coming in contact with aerosol. The results are evaluated as per the PCA
reaction test procedure described above.
EXAMPLE XVIII
Aerosol Suspension A mixture of N-(5-tetrazolyl)-1-oxo-lH-6-methoxypyrimido[1,2-a]-quinoline-2-carboxamide (antiallergy agent) and the other ingredients under (a) lS in the examples below are micronized to a particle size of 1 to 5 microns ;n a ball mill. The resulting slurry is then placed in a container equipped with a valve and propellant (b) introduced by pressure filling through the valve noz-le to a gauge pressure of approximately 35-40 pounds per square inch at 20C.
Suspension A Percent (a) Antiallergy agent 0.25 Isopropyl myristate 0.10 Ethanol 26.40 (b) 60-40% mixture of 1,2-dich,lorotetrafluoro- 73.25 ethane-l-chloropentafluoroethane Suspension B Percent (a) Antiallergy agent 0.25 Ethanol 26.50 (b) 60-40% mixture of 1,2-dichlorotetrafluoro- 73.25 ethane-l-chloropentafluoroethane PREPARATION A
Ethyl l-Oxo-lH-6-methoxyprimido~1,2-a]quinoline-2-carboxylate (1) A mixture of 2-amino-4-methoxyquinoline (34 g., 0.196 mole) and diethyl ethoxymethylenemalonate (46.8 g., 0.216 mole) is heated on a steam bath. A clear melt forms within about 10 minutes and within about twenty minutes begins to resolidify. The mixture is heated a total of 45 minutes and is then cooled. The product, diethyl 4-methoxy-2-quinolylaminomethylene-malonate, is crystallized from ethanol (350 ml.) as a fluffy solid; m.p. 136.5-137.5~C.
Analysis: Calc'd for C18H20N205: C, 62.78; H, 5.85; N, 8.14 %

Found : C,`62.72; H; 6.10, N, 8.37 %(2) To Dowtherm A ("Dowtherm" is a trademark) (350 ml.) at 100C. is added the product from (1) (55 g., 0.16 mole) and the resulting clear yellow solution heated to 230-233C. for 1.75 hours. The reaction mixture is cooled, diluted with ethyl acetate (500 ml.) and then extracted with lN hydrochloric a¢id ~3 x 120 ml.~. The extracts are combined, made basic with 20% ammonium hydroxide and chilled to precipitate the product. It i8 filtered and recrystal-lized successively from ethanol, benzene - cyclohexane (1:1) and ethanol to give 15.5 g. of yellow crystals; m.p. 130-130.5C.
(3) Alternatively, the procedure of Preparation A(2) is repeated but starting with 3.5 g. of diethyl 4-methoxy-2-quinolylaminomethylenemalonate.
The product is recovered by cooling the reaction mixture, diluting it with cyclohexane (150 ml.) to precipitate the crude product as a brown gummy materi-al. It is obtained in crystalline form by heating the diluted reaction mix-ture to boiling and filtering the hot mixture. Upon cooling the product pre-cipitates as yellow crystals and is separated by filtration. Yield = 1.1 g.
Further purification is achieved by recrystallizing it from ethanol.

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PREPARATION B
Following the procedures of Preparation A(l) and A(3), the compounds listed below are prepared from appropriate reactants. In most instances, the product separates in the form of crystals upon dilution of the reaction mixture with cyclohexane and hot filtration of the mixture is unnecessary.
. The following are thus prepared:

1 ~1 2 ~ I
d`~

~3 ~1 R2 m.p. (C.) OCH3 Cl H 213-214 OCH3 CH3 H 191.5-192.5 OCH3 OCH3 H 200-201.5 OCH3 OC2H5 H 163.5-164.5 : OCH3 H F 141-143 OCH3 F H 175.5-177 .

.. . .. ,. . . - - - .

-`-` 1060441 PREPARATION C
l-Oxo-lH-6-methoxypyrimido[1,2-a]quinoline-2-carboxylic Acid A mixture of ethyl l-oxo-lH-6-methoxypyrimido[1,2-a]quinoline-2-carboxylate (3.0 g.) and concentrated hydrochloric acid (60 ml.) is heated on a steam bath for a half hour. It is then cooled and filtered to give 0.87 g.
of the title product. It is recrystallized from N,N-dimethylformamide; m.p.
219~C. (dec.).
In like manner, the products of Preparation B are hydrolyzed to the corresponding acids.

- ~ih 2 ~ N

R3 Rl R2 m.p. (C.) OCH3 Cl H 239 (dec.) OCH3 CH3 H 247 (dec.) OCH3 H OCH3 230 (dec.) OCH3 H C1 234 (dec.) OCH3 OCH3 OCH3 245 (dec.) OCH3 OC2H5 H 237 (dec.) C2HS H H 205 (dec.) OCH3 H F 196-198 (dec.) OCH3 F H 265-268 (dec.) PREPARATION D

(1) A mixture of 2-amino-4-chloroqui~oline ¢15.5 g~, 0~087 mole) and diethyl ethoxymethylenemalonate (20.8 g., 0.096 mole) i6 heated on a steam bath for 45 minutes, Isopropanol ¢75 ml.) i8 added to the hot clear melt which is then cooled. The product separates and ;s filtered, washed with isopropanol and dried. Yield = 26.0 g. of white solid; m.p. 108.5-109.5C.
It ls used directly in step ~2) without further purification.
Recrystallization from ethanol affords an analytical sample, m,p.
109-110C.
(2) The intermediate diethyl 4-chloro-2-quinolylaminomethylenemalonate from step ~ 26 g.) is added to Dowtherm A C~IDowtherml~ is a trademark) ¢75 ml.) at 100C. The resulting clear solution is heated to 235-237C. for 80 minutes and then cooled. Hexane ~100 ml.) is added to the reaction mixture and the product which precipitates recovered by filtration, washed with hexane and dried. It is recrystallized from acetonitrile, m.p. 178-179C.
The following compounds are prepared from appropriate reactants by the procedures of Preparation D CR3 = Cl, Br) and A(l) and A~3) (R3 =
alkoxy and Cs R3 ~0 ::

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Claims (28)

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

1. A process for the production of pharmaceutically active compounds of the formula:

wherein each of R1 and R2 is independently selected from hydrogen, C1-5 alkyl, C1-5 alkoxy, fluoro and chloro or R1 and R2 in combination may form an -O-CH2-CH2-O- or -O-CH2-O- group and R3 is selected from chloro, bromo and C1-5 alkoxy wherein a dehydration coupling of an acid of the formula with a 5-amino tetrazole is effected.

2. A process according to claim 1, where said acid is first contacted with a dehydrative coupling agent and is subsequently contacted with 5-amino tetrazole.

3. A process according to claim 1, where there is employed as coupling agent a compound selected from N,N'-carbonyldiimidazole, N,N'-carbonyl-di-s-trizine, ethoxyacetylene, 1,1-dichlorodiethylether, diphenyl-ketene p-tolyimine, N-hydroxyphthalimide, N-hydroxypiperidine, ethylene chlorophosphite, diethyl ethylene pyrophosphite, N-ethyl-5-phenylisoxazolium-3'-sulfonate, phenylphosphoroditl-imidazolate) and carbodiimides such as dicyclohexylcarbodiimide, 1-cyclohexyl-3-(2-morpholinomethyl)carbodiimide, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, l-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide hydrochloride and diethyl cyanamide.

4. A process according to any one of claims 1 to 3, wherein a mole ratio of acid:coupling agent:5-amino tetrazole of from 1:1:1 to 1:1.1:1.1 is employed.

5. A process according to any of claims 1 to 3, wherein there is employed as coupling agent N,N'-carbonyldiimidazole, and that the process is carried out at a temperature of from 85 to 100°C. in the presence of N,N-dimethyl formamide as solvent.

6. A process according to any of claims 1 to 3, wherein an acid of the formula where X is C1 or Br is dehydratively coupled with 5-amino tetrazole and the product is reacted with a C1-5 alkanol.

7. A process according to any of claims 1 to 3, wherein the said acid of formula is prepared by hydrolysis of the corresponding ester of the acid with a C1-5 alkanol.

8. A process according to any one of claims 1 to 3, wherein said acid of formula is prepared by cyclization of wherein R is a C1-5 alkyl group followed by hydrolysis of the ester so obtained.

9. A process according to claim 8, wherein the compound to be cyclized is prepared by condensation of the corresponding 2-amino-quinoline and a dialkyl ethoxy methylenemalonate.

10. A method according to claim 1, wherein each of R1 and R2 is hydrogen and R3 is lower alkoxy.

11. A method according to claim 1, wherein R1 is hydrogen, R2 is 8-lower alkoxy and R3 is ethoxy.

12. A method according to claim 1, wherein R1 is 8-lower alkoxy, R2 is 9-lower alkoxy and R3 is methoxy.

13. A method according to claim 1, wherein R1 is hydrogen, R2 is fluoro and R3 is methoxy.

14. A method according to claim 10, wherein R3 is methoxy.

15. A method according to claim 11, wherein R2 is 8-methoxy.

16. A method according to claim 10, wherein R3 is ethoxy.

17. A method according to claim 12, wherein R1 is 8-methoxy and R2 is 9-methoxy.

18. A method according to claim 13, wherein R2 is 9-fluoro.

19. A compound of the formula wherein each of R1 and R2 is selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, chloro, and fluoros;
R1 and R2 when taken together are alkylene-dioxy and are selected from the group consisting of methylenedioxy and ethylenedioxy;
R3 is selected from the group consisting of chloro, bromo and lower alkoxy;
and the pharmaceutically-acceptable cationic salts thereof, whenever obtained by the dehydrative coupling of an acid of the formula and a 5-amino tetrazole.

20. A compound according to claim 19, wherein each of R1 and R2 is hydrogen and R3 is lower alkoxy whenever obtained by the process of claim 10.

21. A compound according to claim 19, wherein R1 is hydrogen, R2 is 8-lower alkoxy and R3 is ethoxy whenever obtained by the process of claim 11.

22. A compound according to claim 19, wherein R1 is 8-lower alkoxy, R2 is 9-lower alkoxy, and R3 is methoxy whenever obtained by the process of claim 12.

23. A compound according to claim 19, wherein R1 is hydrogen, R2 is fluoro and R3 is methoxy whenever obtained by the process of claim 13.

24. The compound according to claim 19, wherein each of R1 and R2 is hydrogen and R3 is methoxy whenever obtained by the process of claim 14.

25. The compound according to claim 19, wherein each of R1 and R2 is hydrogen and R3 is ethoxy whenever obtained by the process of claim 16.

26. The compound according to claim 19, wherein R1 is hydrogen, R3 is ethoxy and R2 is 8-methoxy whenever obtained by the process of claim 15.

27. The compound according to claim 19, wherein R3 is methoxy and R1 is 8-methoxy and R2 is 9-methoxy whenever obtained by the process of claim 17.

28. The compound according to claim 19, wherein R1 is hydrogen, R2 is 9-fluoro and R3 is methoxy whenever obtained by the process of claim 18.