IE44230B1 - 1,3-diaza-bicyclo/3,2,0/ heptane derivatives - Google Patents

Abstract

The novel compounds of the general formula I, in which R<2> and R<4> have the meaning given in Claim 1, are valuable antibiotics. In order to prepare them, a compound of the general formula VIII is reacted with an acyl halide of the formula R<4>-Hal.

Description

This invention concerns l,3-diazabicyclo[3.2.0jheptan -7anes which have anti-bacterial activity.

The basic penicillin nucleus is a 4-thia-l-azabicyclo [3.2.0] hsptan-7-one ring system having the skeletal structure: Canpounds having this ring system have been the cbject of intense research and numerous scientific articles and patents over the past two decades.

Within the last few years, attention has been directed to 10 the synthesis of canpounds having analogous ring systems. Among these penicillin analogs are 1-azabicyclo j3.2.ojheptane-7-one systsms [Moll et al-, Z,· Maturforsch B 24:942 (1969) and Earle et£,, J. Chem. Soc. C 2093 (1969) and Lowe et al,.. /. Chem. Soc. Chem. Comm. 328 (1973)]]; 4-oxa-l-azabicyclo [3.2.oJ heptan-7-one systems [Deshpande et al_., /. Chem. Soc. _£ 1241 (1966); Wolfe et al,, Can. J. Chem. 50:2902 (1972); Golding et al., j-^hem. Soc. Chem. Comm. 293 (1973); German Offenlegungschriften 2,219,601, 2,356,862 and 2,411,856; Japanese Patent Specification 9,007,263 and Netherlands Patent Specification No. 7,313,896]; 1,4-diazabi cyclo [3,’,o]heptan-7-one systems [Bose et al., J. Org. Chem. 38:3437 (1973) and German Offenlegungsschrift 2,219,60]] and a 3-thia-l-azabicyclo [3.2.oJheptan-7-one system;_Bose et al., 0. Chem. Soc. C 188 (1971)].

The present invention provides 1,3-diazabicyclo [3.2.ojheptan -7-one penicillin analogs which are represented by the formula: in which: R1 is hydrogen or 4423° R2 is phenyl; phenoxymethyl; benzyl; α-aminobenzyl; a-hydroxybenzyl; α-carboxybenzyl; phenyl substituted with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, trifluoromethyl, halo or hydroxy; or benzyl substituted 5 on the phenyl ring with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, trifluoromethyl, halo or hydroxy; R is hydrogen, or an easily removable ester-forming protecting ' group, for example 2,2,2-trichloroethyl, t-butyl, benzyl, 10 benzhydryl, benzyloxymethyl, £-nitrophenyl, £-methoxyphenyl, £-nitrobenzyl or £-methoxybenzyl; and is alkanoyl of from one to five carbon atoms, e.g. acetyl or propionyl; alkoxycarbonyl of from two to five carbon atoms, e.g. ethoxycarbonyl; haloacetyl; dihaloacetyl; benzoyl; benzoyl substituted with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, tri fluoromethyl or halo, e.g. js-anisoyl or £-toluoyl; phenylacetyl; phenylacetyl substituted on the phenyl ring with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, tri fluoromethyl or halo; methanesulfonyl; ethanesulfonyl; benzenesulfonyl; benzyl sulfonyl or £-toluenesulfonyl; and non-toxic, pharmaceutically acceptable salts thereof.

» · -IIt will be recognized that the 2-carboxylic acid group of the compounds of formula I, when R3 1s hydrogen, can be readily converted into a non-toxic pharmaceutically acceptable Salt, for example, a salt formed with the alkali metals such as sodium or potassium, the alkaline earth metals such as calcium, or with the ammonium cation. These salts can be prepared by standard methods. • 4 The expression easily removable ester-forming protecting group is one which has acquired a definite meaning within the penicillin, cephalosporin and peptide arts. Many such groups are known which are used to protect the carboxyl group during subsequent chemical reactions and are later removed by standard methods to give the free carboxylic acid. Known ester-forming protecting groups include 2,2,2-trichloroethyl, C^-Cg-tertiary alkyl, Cg-C?tertiary alkenyl, Cg-Cytertiary alkynyl, C-j-Cg-alkanoylmethyl, phthalimidomethyl, benzoylmethyl, naphthoylmethyl, furoylmethyl, thienoylmethyl, nitrobenzoylmethyl, halobenzoylmethyl, methylbenzoylmethyl, methanesulfonylbenzoylmethyl, phenyl benzoylmethyl, benzyl, nitrobenzyl, methoxybenzyl, benzyloxymethyl, nitrophenyl, methoxyphenyl, benzhydryl, trityl, trimethylsilyl and triethylsilyl. The choice of an ester-forming protecting groups is well within the ability of one skilled in the art. Factors which are considered include the subsequent reaction conditions the group must withstand and the conditions desired for removing the protecting group. Because the novelty of this invention lies within the new bicyclic nucleus, the choice of a protecting group is not critical to the invention.

The compounds of formula I are prepared as shown in Scheme 1 below in which and R4 are defined as above, R5 is an easily removable amine protecting group, X is halogen, preferably chloro, and R3 is an easily removable ester-forming protecting group.

The compounds VI, Via, VII and Vila of Scheme 1, and processes for their preparation, are described and claimed Sn our' Patent Specification No. 1921/80.

The expression an easily removable amine protecting group is a well known term which includes many groups known and used in the penicillin, cephalosporin or peptide synthesis art.

These groups include trityl, t-butoxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl and 1-methoxycarbonyl-2-propenyl. Divalent amine protecting groups include phthaloyl and imineforming groups. The choice of the protecting group depends on various factors including the subsequent chemical reaction conditions and the conditions desired for removing the protecting group. The choice of the protecting group to be used is within the ordinary ability of one skilled in the art.

SCHEME 1 H. C0,CH, \z 2 3 II N ) DMB Ng 'S.s* Jt DMB (II) C02CH3 DMB (III) (IV) DMB = 2,4-dimethoxybenzyl (V) a: III' According to Scheme 1, when the imine resulting from the condensation of methyl glyoxal ate and 2,4-dimethoxybenzylamine is allowed to react with a mixed anhydride of azidoacetic acid, azetidinone II is obtained. Hydrogenation of this compound gives the corresponding amino derivative which can be protected with an amine protecting group by standard methods to give compound III. Treatment of III with potassium persulfate results in removal of the dimethoxybenzyl group to give compound IV which upon reduction, for example with sodium borohydride, gives V. Reaction of the tosylate derivative of V with an azide such as sodium azide gives the corresponding azidomethyl compound VI. The amine protective group is removed, for example by treatment of VI with trifluoroacetic acid, and the resulting amino compound Vl-a is acylated according to standard procedures to give VII. Reduction of VII with subsequent reaction of the aminomethyl compound VH-a thus formed with a glyoxalic acid derivative, the carboxylic acid function being suitably protected with an easily removable ester-forming protecting group, gives compound VIII. Treatment of VIII with an acyl halide (R4-X) gives the 1,3-diazabicyclo compounds of formula I where is R2C0- and R and is an easily removable ester-forming protecting group.

When R4 is formyl, the corresponding compounds of formula I where R1 is R3CO- and R^ is an easily removable ester-forming protecting group are also prepared by treatment of VIII with N-formyl-imidazole in the presence of a catalytic amount of imidazole hydrochloride. Cleavage of the ester-forming protecting group gives the compounds of formula I where R1 is R^CO- and R3 is hydrogen.

When the amine protective group selected is itself a group desired as a 6-substituent in the final product, viz. one of the formula.R2CO- where R2 is defined as above, the steps of deblocking of the amine function and subsequent acylation can be eliminated from the reaction sequence depicted in Scheme 1.

When R1 is hydrogen, the corresponding compounds of formula I are, preferably, prepared by removal of the amine and carboxylic acid protective groups from a 3-substituted - 6β - benzyloxycarbonylami no - 7 - oxo - 1,3 - diazabicyclo [3.2.6]heptane - 2 - carboxylic acid benzyl ester, for example by hydrogenolysis. The 3 - substituted6β - benzyloxycarbonylamino - 7 - oxo - 1,3 - diazabicyclo [3.2,0_] heptane - 2 - carboxylic acid benzyl esters are prepared by the methods described above.

Alternatively, the 3-azido-acetidinone II can be converted into a 3-amino-2-tosyloxymethyl derivative by cleavage of the 2,4-dimethoxybenzyl group, followed by reduction of the ester function, conversion of the product hydroxymethyl compound into the tosylate and reduction of the azide moiety, all as described above.

The resulting 3-amino-azetidinone can then be acylated or protected as required and converted to the desired 1,3-diazabicyclo [3.2.0] heptane compound.

The starting materials, in particular compounds of formula VH-a, for the compounds of this invention can be prepared as described and claimed in our Patent Specification ϊίύ. 1921/80.

It is recognized that, due to asymmetric carbon atoms both in the bicyclic e-lactam ring system and in some acyl side chains, stereoisomers will exist. All of these isomers, including separated isomers and mixtures thereof, are included within the scope of this invention.

The compounds of formula I are useful as antibacterial agents.

For example, the compound 3- acetyl - 7 - oxo - 6β phenoxyacetylamino - 1,3 - diazabicyclo Jj3.2.o] - heptane - 2 carboxylic acid exhibited activity against Staphylococcus aureus, jl. subtilis and other bacteria in in vitro testing. In addition, the I compounds of formula I where R is hydrogen are useful as chemical intermediates in the preparation of novel bicyclic g-lactams which have antibacterial activity.

The invention further provides pharmaceutical compositions having antibacterial activity which comprise a pharmaceutical carrier containing an active but non-toxic quantity of a compound of formula I or a non-toxic, pharmaceutically acceptable salt thereof, as well as methods of combatting bacterial infections by administering a compound of formula I or a non-toxic, pharmaceutically acceptable salt thereof to a non-human infected host in a non-toxic amount sufficient to combat such infections. The preferred route of administration is -by parenteral injection, such as subcutaneously, intramuscularly or intravenously, of suitably prepared sterile solutions or suspensions containing an effective, non-toxic amount of a cephalosporin compound of the invention. 423Ό -¾ Λ Μ $ t ξ.

The compounds of formula I can be formulated and administered in the same manner as other cephalosporins. The dosage regimen comprises administration, preferably by injection, of an active but non-toxic quantity of a compound of formula I. The precise dosages are dependent upon the age and weight of the subject and on the infection being treated, and they can be determined by those skilled in the art based on the data disclosed herein compared with that available to the art attained with known cephalosporins.

The following Examples illustrate the invention but are not to be construed as limiting the scope thereof. All temperatures are in degrees Centigrade (°C) unless otherwise indicated.

PREPARATION 1 Methyl cis-3-azido-l-(2,4-ditnethoxyben2yl)-4-oxoazetidine -2-carboxylate To a mixture containing 16.82 g (0.101 mole) of 2,4-dimethoxybenzylamine and anhydrous magnesium sulfate in 150 ml of methylene chloride at 25° was added a solution of 10.05 g (0.114 mole) of methyl glyoxalate in 20 ml of methylene chloride.

The reaction mixture was stirred at room temperature overnight (15 hours) and then was filtered and the solvents were removed jn vacuo to afford the imine of Scheme 1 as a dark orange gum.

To a solution of 15.1 g (0.149 mole) of azidoacetic acid in 130 ml of anhydrous methylene chloride at 0° (ice bath) was added dropwise 21.0 ml (0.15 mole) of trifluoroacetic anhydride. The mixture was stirred at 0° for 15 minutes and then 20.8 ml (0.15 mole) // 4a of triethylamine was added dropwise. Stirring was continued for an additional 45 minutes and then the entire reaction mixture was transferred under argon into an addition funnel which was cooled externally by dry ice. The addition funnel was attached to a flask containing the imine from above, 200 ml of anhydrous methylene chloride and 20.8 ml (0.15 mole) of triethylamine. The solution of the mixed anhydride obtained was added dropwise from the addition funnel to the solution of imine at 0°. Stirring was continued at 0° for 1 hour and then the dark reaction mixture was transferred to a separatory funnel and washed with water, aqueous sodium bicarbonate and brine and dried over anhydrous magnesium sulfate. The solvents were removed in vacuo and the residue was chromatographed on 300 g of silica gel (70 - 230 mesh) affording an off-white solid which was further purified by trituration with ether to give the title compound as a white solid; tic; benzene :ethyl acetate (1:1), silica gel GF, Rf =0.64; mp 82-84° (ethyl acetatehexane).

PREPARATION 2 Methyl cis-4-oxo-3-phenoxyacetylaminoazetidine-2-carboxylate A mixture containing 10.0 g (0.0312 mole) of methyl cis3-azi do-1-(2,4-di methoxybenzyl)-4-oxoazeti di ne-2-carboxylate. 1.0 g of 10% palladium on carbon and 200 ml of ethanol was hydrogenated at 60 psi of hydrogen at 40-45° for 2 hours. The reaction mixture was allowed to cool to 25° and was filtered through ·’ Celite (trade mark). After removing the solvents in vacuo there remained a clear, yellow gum. The crude amine was taken up in 100 ml of anhydrous methylene dichlorideand was cooled to 0° in an ice bath. To this solution was added 4.32 ml (0.0312 mole) of : triethylamine, followed by the slow addition of a solution of .32 g (0.0312 mole) of phenoxyacetyl chloride in 40 ml 'of methylene dichloride. The mixture was stirred at 0° for 1 hour, then extracted successively with water, aqueous hydrochloric acid, aqueous sodium bicarbonate and brine and was dried over anhydrous magnesium sulfate. Filtration, followed by removal of the solvent in vacuo, afforded a yellow solid. This material was partially dissolved in ether*, cooled to -25° and filtered to give methyl cis - 1 - (2,4 - dimethoxybenzyl) - 4- oxo - 3 - phenoxyacetylaminoazetidine -2 - carboxylate as a white solid; tic; benzene:ethyl acetate (1:1), silica gel, Rf = 038;; mp 115.5-116.0° (ethyl acetate-hexane). ., To 900 ml of acetonitrile, whicfi had been thoroughly degassed with argon, was added 30.0 g (0,070 mole) of methyl cis-1*-2,4-dimethoxybenzyl)-4-oxo-3-phenoxyacetylaminoazetidine-220 carboxylate and the solid was rinsed into the reaction vessel with an additional 50 ml of degassed acetonitrile. This solution res heated to 78° under argon and to it was added a degassed solution of 75.6 g (0.28 mole) of potassium persulfate and 37.5 g (0.14 mole) of sodium monohydrogen phosphate in 1400 ml of water. Addition of the.aqueous solution was made in six portions of 250 ml over a period of 1 hour while maintaining the external temperature bqtween 78° and 82°. After cooling the reaction mixture, the acetonitrile was removed by evaporation. Sodium chloride was added to the concentrated reaction mixture and it was extracted four times with ethyl acetate. The combined ethyl acetate extracts were dried (MgS04), filtered and concentrated in vacuo to approximately 100-200 ml. Addition of ether (ca. 300 ml) followed by low temperature (-25°C) crystallization, afforded the title compound; tic: silica gel GF, ethyl acetate, Rf = 0.44; ethyl acetate:benzene (1:1), RF = 0.21; mp T4O-1410 (ethyl acetate-hexane).

PREPARATION 3 ci/-2-Hydroxymethyl-4-oxo-3-phenoxyacetylaminoazetidine To a solution of 13.5 g (0.049 mole) of methyl cis-4-oxo-3phenoxyacetylaminoazetidine-2-carboxylate in 975 ml of tetrahydrofuran and 100 ml of water 0° (ice bath) was added a cold solution of 3.75 g (0.099 mole) of sodium borohydride in 250 ml of water over a period of 10 minutes. The solution was stirred at 0° for 40 minutes and then glacial acetic acid was added dropwise until hydrogen evolution ceased. Solid sodium bicarbonate and sodium chloride were added and this mixture was extracted five times with 250 ml portions of ethyl acetate.

After drying the combined extracts (MgSOz;), the solvent was removed in vacuo The resulting residue was dissolved in ethyl acetate, clarified with Norit (trade mark) and allowed to crystallize to give the title compound; tic: ethyl acetate, silica gel GF, Rf = 0.10; mp 153-154° (ethyl acetate).

PREPARATION 4 cis-2-Azidomethy1-4-oxo-3-phenoxyacety1 ami noazeti d i ne To a solution of 4.30 g (0.022 mole) of 98% £-toluenesulfonyl chloride in 24 ml of anhydrous pyridine at 0° (ice bath) was added 2.64 g (0.011 mole) of cis-2-hydroxymethyl-4-oxo-3-phenoxyacetylanrinoazetidine in one portion. The solution was stirred at 0° for 3 hours, then was stored at -25° overnight. After warming to 0°, 1.0 ml of 85% lactic acid was added and stirring was continued for 1 hour. The reaction mixture was poured into ethyl acetate and extracted successively with water, dilute aqueous hydrochloric acid, aqueous sodium bicarbonate and brine and was dried (MgSO^). Filtration, followed by removal of the solvent in vacuo, resulted in a yellow solid. Clarification of a hot solution of this material in ethyl acetate (375 ml), followed by the addition of hexane (200 ml) and recrystall izati on, afforded cis-4-oxo-3-phenoxyacetylamino-22-toluenesulfonyloxymethylazetidine; tic: ethyl acetate, silica gel GF, Rf = 0.47; mp 136° (dec.).

A mixture containing 1.131 g (2.8 mmole) of cis-4-oxo-3 phenoxyacetylami no-2-£-to1uenesulfonyloxymethylazetidi ne, 0.961 g (14.8 mmole) of sodium azide and 25 ml of anhydrous Ν,Ν-dimethylformamide was heated under argon at 40° for 6 hours, then at ambient temperature for 24 hours. The reaction mixture was poured into ethyl acetate and was washed with water. The combined aqueous washes were extracted once with ethyl acetate and the ethyl acetate fractions were combined and extracted with brine. After drying the ethyl acetate solution (MgSO^) and filtering, the solvent was removed in vacuo to afford a yellow semi-crystalline residue. This residue was slurried in methylene dichloride and chromatographed on 25 g of silica gel (70-230 mesh). The 1:1 ethyl acetate:methylene dichloride fractions afforded the title compound; tic: ethyl acetate, silica gel GF, Rf = 0.38; mp 142-143° (dec.) (ethyl acetate-hexane).

PREPARATION 5 cis-2-Az i domethyl -3-.t-butoxycarbonyl ami no-4-oxoazeti di ne A mixture containing 10.0 g (0.0312 mole) of methyl cis-3azido-1 - (2,4-d imethyloxybenzyl)-4-oxoazeti d i ne-2-carboxylate, 1.0 g of 10% palladium on carbon and 200 ml of ethanol was hydrogenated for 2 hours at 40-45° and 60 psi of hydrogen. The reaction mixture was allowed to cool to 25° and was filtered through a filter-aid. After removing the solvents j_n vacuo there remained methyl cis-3- amino - 1 - (2,4-dimethoxybenzyl)-4-oxoazetidine-215 carboxylate.

A solution of 5.5 g (18.8 mmole) of methyl cis-3-amino-l(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 100 ml of dry toluene was cooled to -78° and 2.5 ml (18.8 mmole) of triethylamine was added followed by rapid addition of 35 ml (42 mmole) of a 125» solution of phosgene in benzene. The mixture was stirred for 15 minutes at -78°, and 3 hours at -45° (acetonitrile-dry ice), then warmed to room temperature and concentrated to half volume in vacuo. To the resulting solution was added 50 ml of t-butanol and the mixture was stirred at room temperature overnight. The solvents were removed in vacuo and the residue diluted with ethyl acetate and filtered.

The filtrate was transferred to a separatory funnel and washed with 5% aqueous sodium bicarbonate, 5% hydrochloric acid and brine, dried (MgSO^) and evaporated to dryness. Recrystallization of the crude, crystalline product from ether gave methyl cis-3-tbutoxycarbonylamino-l-(2,4 - dimethoxybenzyl)-4-oxoazetidine-2carboxylate, mp 134-135°.

A solution of 10.5 g (26.7 mmole) of methyl 3-jt-butoxycarbonylamino -1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 500 ml of acetonitrile was degassed with argon and warmed to 80°. A degassed solution of 15 g (55.5 mmole) of potassium persulfate and 7.5 g (28 mmole) of sodium monohydrogen phospahate in 150 ml of water was added in five portions over 1 hour. The reaction mixture was stirred at 80-85° under argon for 2-3 hours until all starting material had disappeared (tic). The reaction mixture was cooled, concentrated in vacuo and shaken with ethyl-acetate water. The organic phase was washed with dilute hydrochloric acid, aqueous sodium bicarbonate solution and brine; dried (MgSO^) and evaporated to dryness. The residue was chromatographed on silica gel with 1:1 benzene-ethyl acetate to afford pure product which crystallized from ethyl acetate-hexane to give methyl cis-3-t-butoxy-carbonylamino-4oxoazetidine-2-carboxylate, mp 140-144°.

Sodium borohydride reduction of methyl cis-3-t-butoxycarbonylamino -4-oxo-azetidine-2-carboxylate as described in Preparation 3, followed by conversion of the 2-hydroxymethylazetidine product to the 44330 j> to!uenesulfonate derivative, mp 160-162° (d), and reaction of the derivative with sodium azide as described in Preparation 4 gives the title compound.

PREPARATION 6 cis - 3 - Amino - 2 - azidomethyl - 4 - oxoazetidine cis - 2 - Azidomethvl - 3 - t - butoxycarbonylamino - 4 oxoazetidine (ca. lg) is dissolved in 2 ml of methylene chloride and the solution is cooled to 0° and treated with 0.5 ml of trifluoroacetic acid for 30 minutes at 0°. The solution is washed with 5% aqueous sodium bicarbonate and extracted with dilute hydrochloric acid. The aqueous phase is neutralized and extracted with ethyl acetate. Evaporation of the solvent gives the title compound.

PREPARATION 7 ci s-3-Ami no-4-oxo-2-j>tol uenesul fonyl oxymethyl azetidine A degassed solution of 3.8 g (0.012 mole) of methyl cis-3-azido-l-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate was treated with potassium persulfate and sodium monohydrogen phosphate as described in Preparation 2 to give methyl cis-3-azido-420 oxoazetidin6-2-carboxylate which was purified by chromatography on silica gel with benzene-ethyl acetate as eluant.

Methyl £i£-3-azido-4-oxoazetidine-2-carboxylate was reduced with sodium borohydride as described in Preparation 3 and the product was chromatographed on silica gel with ethyl acetate as eluant to give cis-3-azido-2-hydroxymathyl-4-oxoazetidine. cis - 3 - Azido - 4-oxo-2-£ - toluenesulfonyloxvmethylazetidine was prepared from cis-3-azido-2-hydroxymethyl-4-oxoazetidine according to the procedure of Preparation 4.

Zinc dust (2-0 g- 0.03 mole) was slowly added with cooling to a solution of 5.0 g (0.011 mole) of cis-3-azido-4-oxo-2-ptoluenesulfonyloxymethylazetidine in 50 ml of 50% aqueous acetic acid.

The reaction mixture was stirred for 30 minutes and filtered. The solids were washed with water and the filtrate v/as saturated with hydrogen sulfide, filtered and concentrated to near dryness. The residue was dissolved in ethyl acetate-water and the pH was adjusted to 8.0 by addition of sodium carbonate and sodium hydroxide solutions.

The layers were separated and the aqueous phase was extracted twice with ethyl acetate. The extracts were combined, dried (MgS04) and evaporated to dryness to give the title compound.

PREPARATION 8 cis-2-Aminomethyl-4-oxo-3-mandeloylami noazeti di ne When cis-3-amino-4-oxo-2-p-to1uenesulfonyloxymethylazetidine Ts reacted with O-benzylmandeloyl chloride according to the procedure described in Preparation 2 and the product is subsequently converted to the corresponding 2-azidomethy! compound which is subsequently reduced with zinc and acetic acid as described in Example 2, cis - 2 aminomethyl - 3 - (a-benzyloxyphenylacetylamino)-4-oxoazetidine is obtained. -5 A suspension of 14 mg of 10% palladium on carbon and 0.06 mole of cis-2-amino methyl-3-(«-benzyloxypheny1acetylamino)-4-oxoazetidine in ca. 2 ml of anhydrous ethyl acetate is· hydrogenated at room temperature and atmospheric pressure.

The reaction mixture is filtered and the filtrate is evaporated to dryness to give the title compound.

PREPARATION 9 Reaction of cis-3-amino-4-oxo-2-p-toluenesulfonyloxymethylazetidine with a halide of an acid listed helow, suitably protected as necessary: benzoic acid jo-toluic acid 4-ethylbenzoic acid 4-t-butylbenzoic acid m-anisic acid 4-n-butoxybenzoic acid 2-chlorobenzoic acid 4-bromobenzoic acid 4-hydroxybenzoic acid 3- trifluoromethyl benzoic acid phenylacetic acid α-aminophenylacetic acid u-carboxyphenylacetic acid 4- fluorophenylacetic acid 3- hydroxyphenylacetic acid 4- trifluoromethylphenylacetic acid according to the procedure described in Preparation 2, followed by conversion of the products thus formed to the corresponding 2-azidomethyl compounds as described in Preparation 4, gives the following azetidine intermediates after removal of any protective groups: cis-2-azi domethy!-3-benzoylami no-4-oxoazeti dine cis-2-azidome thyl-4-oxo-3- (jo-toluoyl ami no) azetidine cis-2-azidomethyl-3-(4-ethylbenzoyl ami no)-4-oxoazetidi ne cis22-azidomethyl-3-(4-/-butylbenzoylamino)-4-oxoazetidine cis-3-(m-ani soylami no)-2-azi domethyl-4-oxoazetidi ne cis-2-azidomethyl-3-(4~n-butoxybenzoylanrino)-4-oxoazetidine cis-2-azidomethyl-3-(2-chlorobenzoylami no)-4-oxozeti di ne cis^-2-azidomethyl-3-(4-bromobenzoylamino)-4-oxoazetidine cis-2-azidomethyl-3-(4-hydroxybenzoylami no(-4-oxoazetidi ne 10 cis-2-azidomethyl-4-oxo-3-(3-tri f 1uoromethylbenzoyl ami no)azeti di ne cis-2-azidomethyl-4-oxo-3-phenylacetyl ami noazetidi ne cis-3-(o-aminophenylacetylamino)-2-azidomethyl-4“Oxoazetidine cis-2-azidomethy1-3-(a-carboxypheny1acetylamino)-4-oxoazetidine cis-2-azidomethyl-3-(4-f1uorophenylacetyl ami no)-4-oxoazeti di ne cis-2-azi domethyl-3-(3-hydroxyphenylacetylami no)-4-oxoazetidine cis-2-azi domethyl-4-oxo-3-(4-tri f1uoromethylphenylacetyl ami no)azeti dine PREPARATION 10 cis-2-Aminomethyl-4-oxo-3-phenoxyacetylaminoazetidine A suspension of 0.499 g (1.81 nmole) of cis-2-azidomethyl-4-oxo2Q 3-phenoxyacetylaminoazetidine and 0.189 g of 10% palladium on carbon in 25 ml of absolute ethanol was hydrogenated at atmospheric pressure and at 40° for 1 hour. The solution was filtered through Celite and the solvent was removed in vacuo to afford the title compound as a colourless gum.

PREPARATION Π Reduction of a 2-azidomethyl-3-substituted-4~oxoazetidine listed in Preparation 9 according to the procedures described in Preparation 8 or Preparation 10 gives the following 2-aminomethyl compounds: ci 5-2-ami nomethyl-3-benzoylamino-4-oxoazetidine cis-2-aminomethyl- 4-oxo-3- (£-to1uoylami no Jazetidine cis-2-aminomethyl-3-(4-ethylbenzoyl ami no)-4-oxoazeti di ne cis-2-aminomethyl-3-(4-t-butylbenzoyl amino)-4-oxoazetidine cis-2-aminomethyl-3-(m-ani soylami no)-4-oxoazeti di ne cis-2-aminomethyl-3-(4-n-butoxybenzoylamino)-4-oxoazetidi ne cis-2-aminomethyl-3-(2-chlorobenzoylami no)-4-oxoazeti di ne cis-2-aminomethyl-3-(4-bromobenzoyl ami no)-4-oxoazeti di ne cis-2-anrinomethyl-3-(4-hydroxybenzoylamino)-4-oxoazetidine cis-2-aminomethyl-4-oxo-3-(3-trif1uoromethylbenzoyl amino)azeti dine cis-2-aminomethyl-4-oxo-3-phenvlacetyl ami noazeti di ne cis-2-aminomethyl-3-(α-ami nophenylacety1ami no-3-oxoazetidi ne cis-2-aminomethyl-3-(α-carboxyphenvlacetvlami no)-4-oxoazeti dine cis-2-aminomethyl- 3-(4-f1uorophenylacetvlami no)-4-oxoazetidine cis-2-ami nomethyl - 3- (3-h.ydroxyphenyl acetyl ami no) -4-oxoazeti di ne cis-2-aminomethyl- 4-3-(4-trifluorometh'ylphenylacety]amino)azetidine.

PREPARATION 12 cis-2-Azidomethyl-3-(4,5-diphenyl-2-oxo-4- oxazo!in-3-yl)-4-oxoazetidine To a mixture containing 16.82 tj (0.101 mole) of 2,4-dimethoxybenzylamine and anhydrous magnesium sulfate in 150 ml of methylene chloride at 25° is added a solution of 10.05 g (0,114 mole) of methyl glyoxalate in 20 ml 44330 ’ ; of methylene chloride. The reaction mixture is stirred at room temperature overnight (15 hours) and then is filtered. The solvents are removed in vacuo to afford methyl N-(2,4-dimethoxybenzyl)-iminoacetate as a dark orange gum.

A mixture of 4,5-diphenyl-2-oxo-4-oxazo1in-3-ylacetic acid (2.1 q, 7.1 mmole) [j. Org. Chem., 38. 3034 (T973)J , 5 ml of thionyl chloride and 20 ml of methylene chloride is refluxed for 2.5 hours.

After cooling to room temperature the solvent is removed in vacuo and the resulting oil crystallizes on standing. The product is triturated with ether-hexane to give 4,5-diphenyl-2-oxo-oxa zolin-3-ylacetic acid chloride, mp 104-112°.

Methyl N-(2,4-dimethoxybenzyl)iminoacetate (1.43 g) is dissolved in 13 ml of dry methylene chloride and 1 ml of triethylamine and cooled in an ice bath. A solution of 4,5-diphenyl-2-oxo-4-oxazolin-3-ylacetic acid chloride (2.0 g, 6.4 mmole) in 10 ml of methylene chloride is added over a 10 minute period. After one hour, the mixture is washed with water and 5% aqueous sodium bicarbonate, then dried and evaporated to give a red oil which is chromatographed on silica gel to give methyl cis-1-(2,4-dimethoxybenzyl)-3-(4,5-diphenyl-2-oxo-4-oxazo1in -3-yl )-4-oxoazetidine-2-carboxylate.

Methyl cis - 1 - (2,4 - dimethoxybenzyl) - 3 - (4,5 - diphenyl - 2 - oxo - 4 - oxazolin - 3 - yl) - 4 - oxoazetidine - 2 - carboxylate is treated with potassium persulfate and sodium monohydrogen phosphate as described in Preparation 5 to givp methyl cis - 3 - (4,5 - diphenyl - 2 25 oxo - 4 - oxazolin - 3 - yl) - 4 - oxoazetidine - 2 - carboxylate.

Sodium borohydride reduction of methyl cis-3-(4,5-diphenyl-2oxo-4-oxazolin-3-y1)-4-oxoazetidine-2-carboxylate as described in Preparation 3, followed by conversion of the 2-hydroxymethylazetidine product to the £-toluenesulfonate derivative and reaction of this derivative with sodium azide as described in Preparation 4 gives the title compound.

PREPARATION 13 When £-methoxybenzyl alcohol, isoborneol, benzyl alcohol or 2,2,2-trichloroethanol is substituted for t-butanol in Preparation 5 in the reaction with methyl £is-3-amino-l-(2,4-dimethoxybenzyl)-4oxoazetidine-2-carboxylate, methyl cis-1-(2,4-dimethoxybenzyl)-3(ja-methoxybenzyl oxycarbonyl ami no) -4-oxoazeti di ne-2-carboxyl ate, methyl cis-1 - (2,4 - dimethoxybenzyl) - 3 - isobornyloxycarbonylami no - 4 oxoazetidine - 2 - carboxylate, methyl cis-3-benzyloxycarbonylami no -1-(2,4-dimethoxybenzyl)-4-oxo-azetidine-2-carboxy1ate or methyl cis-1 - (2,4-dimethoxybenzyl)-4-oxo-3-(2,2,2-tri chi oroethoxycarbotiyl amino) azetidine-2-carboxylate is obtained, respectively.

Methyl 3 - isobornyloxycarbonylamino - 1 - (2,4 - dimethoxybenzyl) - 4 - oxoazetidine - 2 - carboxylate can also be prepared by treating the 3-amino compound with isobornyloxycarbonyl chloride in the presence of base according to standard procedures: Chem. Pharm. Bull, , 1017 (1972).

Treatment of the methyl cis-1-(2,4-dimethoxybenzyl)-3(substi tuted oxycarbonylami no)-4-oxoazeti di ne-2-carboxylates inenti oned above with potassium persulfate and sodium monohydrogen phosphate as described in Preparation 5 gives the following compounds, respectively: 4423° methyl cis-3-(p-mathoxybenzyloxycarbonylamino)-4-oxoazetidine -2-carboxylate methyl cis-3-isobornyloxycarbonylamino-4-oxoazetidine-2-carboxy1ate methyl £is-3-benzyloxycarbonylamino-4-oxoazetidine-2-carboxylate methyl pis-4-oxo-3-(2,2,2-trich1oroethoxycarbonylamino)azetidine -2-carboxylate.

Sodium borohydride reduction of a methyl cis-3-(substituted oxycarbonylamino) - 4 - oxoazetidine - 2 - carboxylate listed above as described in Preparation 3, followed by conversion of the 2-hydroxymethylazetidine product thus formed to the p-toluenesulfonate derivative and reaction of this derivative with sodium azide as described in Preparation 4 gives the following compounds, respectively: cis-y-azidomethvl-3- (p-methoxybenzyloxycarbonylamino-4-oxoazeti dine cis-2-azidometh.yl-3-isoborn.yl oxycarbonylamino-4-oxoazetidine cis-2-azidomethyl-3-benzyloxycarbonylami no-4-oxoazetidi ne ci s-2-azidomethy!-4-oxo-3-(2,2,2-tri chioroethoxycarbonylami no)azeti di ne.

EXAMPLE 1 3-Acetyl-7-oxo-6p-phenoxyacetylamino-l,3-diazabicyclo [3.2.o]heptane-2-carboxylic acid A suspension of 0.499 g (1.81 mmole) of cis-2-azidomethy!-4oxo-3-phenoxyacetylaminoazetidine and 0.189 g of 10% palladium on carbon in 25 ml of absolute ethanol was hydrogenated at atmospheric pressure and at 40° for 1 hour. The solution was filtered through Celite and the solvent was removed in vacuo to afford a colourless gum which was dissolved in 15 ml of methylene di chloride. Anhydrous magnesium sulfate was added, followed by addition of a solution of 0.314 g (1.91 mmole) of benzyl glyoxalate in 10 ml of methylene dichloride. Anhydrous magneisum sulfate was added, followed by addition of a solution of 0.314 g (1.91 mmole) of benzyl glyoxalate in 10 ml of methylene dichloride. The reaction mixture was stirred at room temperature under argon for 2.5 hours, then was allowed to stand at 0° overnight. After filtering the reaction mixture, the solvents were removed in vacuo to give a semi-crystal!ine residue which was recrystallized from ethyl acetate-hexane to give a semi-crystalline residue M-(ci s-4-oxo-3-phenoxyacetylami no -2-azetidinylmethyl)iminoacetic acid benzyl ester as a colourless solid.

To a solution of 50 mg (0.13 mmole) of N-(cis-4-oxo-3phenoxyacetylamino-2-azetidinylmethyl)iminoacetic acid benzyl ester in 1.8 ml of anhydrous methylene dichloride at 0° under argon was added μ’ (0.20 mmole) of anhydrous pyridine, followed by 14 ul (0,20 mmole) of acetyl chloride. After the reaction mixture had been stirred at 0° for 1 hour, ethyl acetate was added and the resulting mixture was rapidly suction filtered through a sintered glass funnel containing 1.0 g of silica gel. The solvents were removed in vacuo to afford a semi-crystalline yellow gum which was recrystallized from ethermethanol to give 3-acetyl-7-oxo-6g-phenoxyacetylamino-l,3- diazabicyclo|_3.2. epimers; A suspension of 14 mg of 10% palladium on carbon and 28 mg (0.064 mmole) of 3 - acetyl - 7 - oxo - 6s - phenxoyacetylamino Oj heptane-2-carboxylic acid benzyl ester as a nurture of 0-2 tic: ethyl acetate, silica gel GF, Rf = 0.55; mp 148-150°. 1,3 - diazabicyclo L3.2.0]heptane - 2 - carboxylic acid benzyl ester in ca. 2 ml of anhydrous ethyl acetate was hydrogenated at room temperature and atmospheric pressure for 1 hour. The reaction mixture was filtered through Celite and the solvents were removed in vacuo to afford the title compound; tic: 90:8:2 methylene chloride:methanol: acetic acid, silica gel GF, Rf = 0.31.

EXAMPLE 2 - Acetyl-6e-amino-7-oxo-l,3-diazabicyclo[3.2.0jheptane-2carboxylic acid Reacti on of cis-3-anri no-4-oxo-2-£-tol uenesul fonyl oxymethyl azeti dine with benzyl chloroformate according to the general acylation conditions described in Preparation 2 gives cis - 3 - benzyloxycarbonylamino - 4 - oxo - 2 - £ - toluenesulfonylmethyl azetidine, cis - 3 - Benzyloxycarbonylamino -4-oxo-2-£- tol uenesul fonyl oxymethyl azeti dine is converted to cis - 2 azidomethyl - 3 - benzyloxycarbonylamino - 4 - oxoazetidine as described in Preparation 4. ci£-2-Azidomathyl-3-benzyloxycarbonylamino-4-oxoazetidine it treated with zinc dust in 50% aqueous acetic acid as described in Preparation 7. Reaction of the crude reduction product with benzyl glyoxal ate in methylene dichloride as described in the procedure of Example 1 gives N-(cis-3-benzyloxycarbonylamino-4-oxo-2-azetidiny1methyl)iminoacetic acid benzyl ester which, when treated with acetyl chloride according to the procedure of Example 1, gives 3-acetyl-6e-benzyloxycarbonylami no28 7-oxo-l ,3-diazabicyclo[3.2.ojheptane-2-carboxylic acid benzyl ester. Hydrogenolysis of 3-acetyl-6e-benzyloxycarbonylamino-7-oxo1,3-diazabicyclo|_3.2.0jheptane-2-carboxylic acid benzyl ester as described in Example 1 gives the title compound.

EXAMPLE 3 3-Acetyl-6e-mandeloylami no-7-oxo-l,3-diazabicyclo|3.2.θ]heptane-2-carboxylic acid When cis-2-aminomethyl-3-(α-benzyloxyphenylacetyl ami no)-4oxoazetidine is reacted with benzyl glyoxal ate and the product is treated with acetyl chloride, all as described above, 3-acetyl6e-(u-benzyloxyphenylacetylam1no)-7-oxo-l,3-diazabicyclo-[3.2.cT}heptane2-carboxylic acid benzyl ester is obtained. Hydrogenolysis of the benzyl protective groups as previously described gives the title compound.

EXAMPLE 4 When propionyl chloride is substituted in the procedure of Example 1 for acetyl chloride in the reaction with N-(cis-4-oxo-3phenoxyacetylamino-2-azetidinylmethyl)-iminoacetic acid benzyl ester, the following compound of this invention is obtained: 3 - (£ - anisoyl) - 7 - oxo - 6e - phenoxyacetylamino - 1,3 diazabicyclo L3.2.0]- heptane - 2 - carboxylic acid benzyl ester IR: 5.57μ (e-lactam); 5.7μ (ester); ca. 6.00u (amides).

Removal of the benzyl ester protecting group as previously described or by other standard methods gives 7-oxo-6g-phenoxyacetylamino -3-propionyl-1,3-diazabicyclo [3.2. θ]heptane-2-carboxylic acid.

Similarly, 3-propionyl, butyryl and valeryl derivatives 5 of the 7-oxo-l,3-diazabicyclo (3.2.o]-heptane-2-carboxylic acid compounds disclosed herein are prepared.

EXAMPLE 5 Substitution of ethyl chloroformate in the procedure of Example 1 in place of acetyl chloride in the reaction with N-(cis-4-oxo-310 phenoxyacetylamino-2-azetidinylmethyl)iminoacetic acid benzyl ester gives 3-ethoxycarbonyl-7-oxo-6g-phenoxyacetylamino-l,3diazabicycl oj_3.2.0j heptane-2-carboxyl ic acid benzyl ester IR : 5.56μ (β-lactam)', 5.56μ (ester); 5.85 and 5.90μ (amides and carbonate).

Removal of the benzyl ester protecting group as previously described or by other standard methods gives 3-ethoxycarbonyl-7-oxo-5gphenoxyacetylamino-1,3-diazabicycloE3.2.0] heptane-2-carboxylic acid.

In like manner, 3-alkoxycarbonyl derivatives of the other 7-oxo-l,3-diazabicyclo-[3.2.ojheptane-2-carboxylic acid compounds described above are prepared, EXAMPLE 6 Substitution of £-toluoyl chloride or£-anisoyl chloride in the procedure of Example 1 in place of acetyl chloride in the reaction with N-(cis-4-oxo-3-phenoxyacetylamino-2-azetidinylmethyl)iminoacetic acid benzyl ester gives the following compounds of this invention: - oxo - 6s - phenoxyacetylamino - 3 - (£ - toluoyl) - 1,3 diazabicyclo [3.2,θ]- heptane - 2 - carboxylic acid benzyl ester IR: 5.58» (s-lactam); 5.70» (ester): 5.90, 5.96, 6.10» (amides) - (£ - anisoyl) - 7 - oxo - 6s - phenoxyacetylamino -1,310 diazabicyclo [3.2.0]- heptane - 2 - carboxylic acid benzyl ester; mp 148-150°.

Removal of the benzyl ester protecting group as previously described or by other standard methods gives the carboxylic acid compounds of this invention listed below: 7 - oxo - 6β - phenoxyacetylamino - 3 - (£ - toluoyl) - 1,3 diazabicyclo [3.2.0.]- heptane - 2 - carboxylic acid. - (£ - anisoyl) - 7 oxo - 6β - phenoxyacetylamino - 1,3 diazabicyclo [3.2.0]- heptane - 2 - carboxylic acid.

Similarly, the other 7-oxo-l,3-diazabicyclo j[3.2.o]heptane20 2-carboxylic acid esters disclosed herein may be acylated with a benzoyl chloride to give the corresponding compounds of this invention.

EXAMPLE 7 When methanesulfonyl chloride is reacted with N-(ci s-4-oxQ-3-phenoxyacetylami no-2-azetidi nylmethyl)-iminoaceti c acid benzyl ester according to the procedure described in Example 1, 3-methanesulfonyl-7-oxo-6p-phenoxyacetylami no-1,3-diazabicyclo [3.2.0)heptane-2-carboxylic acid benzyl ester; mp 117-120° is prepared.

Removal of the benzyl ester protecting group as previously described or by other standard methods gives 3-methanesulfonyl -7-oxo-6(?-phenoxyacetylamino-l ,3-diazabicyclo [3.2.o3heptane2-carboxylic acid.

Similarly, 3-substituted sulfonyl derivatives of the other 7-oxo-l,3-diazabicyclo £3.2.o]heptane-2-carboxylic acids disclosed herein are prepared.

Claims (17)

1. A compound of the formula in which: R is hydrogen or 2 » r - c - ; R 2 is phenyl; phenoxymethyl; benzyl; α-aminobenzyl; α-hydroxybenzyl; α-carboxybenzyl; phenyl substituted with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, trifluoromethyl, halo or hydroxy; or benzyl substituted on the phenyl ring with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, trifluoromethy!, halo or hydroxy; R is hydrogen or an easily removable ester-forming protecting group; and R is alkanoyl of from one to five carbon atoms; altoxycarbonyl of from two to five carbon atoms; haloacetyl; dihaloacetyl; benzoyl; benzoyl substituted with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms, trifluoromethy! or halo; phenylacetyl; phenylacetyl substituted on the phenyl ring with lower alkyl of from one to four carbon atoms, lower alkoxy of from one to four carbon atoms; trifluoromethy! or halo; methanesulfonyl; ethanesulfonyl; benzenesulfonyl; benzyl sulfonyl or £-toluenesulfonyl; and non-toxic, pharmaceutically acceptable salts thereof.

2. A compound as claimed in claim 1 in which R is an easily removable ester-forming protecting group.

3. A compound as claimed in claim 1 in which R 3 is hydrogen.

4. A compound as claimed in claim 2 in which R 3 is 2,2,2-trichloroethyl, C^-Cg-tertiary alkyl, Cg-c 7 -tertiary alkenyl, Cg-Cy-tertiary alkynyl, C^-Cg-alkanoylmethyl, phthalimidomethyl, benzoylmethyl, naphthoylmethyl, furoylmethyl, thienoylmethyl, nitrobenzoylmethyl, halobenzoylmethyl, methylbenzoylmethyl, methanesulfonylbenzoyl methyl, phenylbenzoylmethyl, benzyl, nitrobenzyl, methoxybenzyl, benzyloxymethyl, nitrophenyl, methoxyphenyl, benzhydryl, trityl, trimethylsilyl or triethylsilyl.

5. A compound as claimed in claim 4 in which R 3 is 2,2,2trichloroethyl, jt-butyl, benzyl, benzhydryl, benzyloxymethyl, jj-nitrophenyl, p-methoxyphenyl, j3-nitrobenzyl or £-methoxybenzyl.

6. A compound as claimed in claim 5 in which R 4 is acetyl, 5 propionyl, ethoxycarbonyl, ^-anisoyl, 2-toluoyl ^or methanesul fonyl.

7. · A compound as claimed in claim 6 in which R is hydrogen.

8. A compound as claimed in claim 6 in which R 1 is

9. A compound as claimed in claim 8 in which R is phenoxymethyl.

10. 10. A compound as claimed in claim 9 being the compound 3-acetyl-7-oxo-6B-phenoxyacety1amino-l,3-diazabicyclo[3.2.Q]heptane-2carboxylic acid benzyl ester.

11. A compound as claimed in claim 3 in which R^ is acetyl, propionyl, ethoxycarbonyl, jj-anisoyl, jr-toluoyl or methanesulfonyl. 15 12. A compound as claimed in claim 11 in which R^ is hydrogen. 13. A compound as claimed in claim 11 in which R^ is 0 2 H R — C 14. A compound as claimed in claim 12 being the compound 3-acetyl- 6g-amino· -7-oxo-l,3-diazabicyclo £3.2.oJ heptane-2-carboxylic acid. 20 15. A compound as claimed in claim 13 2 in which R is phenoxymethyl. 16. A compound as claimed in claim 15 being the compound 3-acetyl-7-oxo-6e -phenoxyacetylamino-!,3-diazabicyclo jj.2.ojheptane -2-carboxylic acid. 17. A compound as claimed in claim 1, as described in any one 5 of Examples I to 7. 18. A process for preparing a compound according to claim 1 where 1 ? R is R -CO-, which comprises reacting a compound of formula r 2 cohn h £ H ^COgR 3 VIII (where R 2 is as defined in claim 1 and R 3 is an easily removable 10 ester-forming protecting group) with an acyl halide of formula R 4 X (where R 4 is as defined in claim 1 and X represents a halogen), cleaving the ester-forming protecting group R 3 when a compound of formula I where R 3 is hydrogen is required, and, if desired,

12. 15 converting the product into a salt thereof. 4423ο

13. 19. A process for preparing a compound according to claim 1 (where R 4 is formyl and R 1 is R 2 -C0-), which comprises reacting a compound of formula VIII (as defined in claim 18) with N-formyl-imidazole (in the presence of a catalytic amount of 5 imidazole hydrochloride) and if desired converting the product into a salt thereof.

14. 20. A process for preparing a compound as claimed in claim 1, substantially as described in any one of Examples 1 to 7.

15. 21. A compound according to claim 1, when prepared by a process 10 according to any one of claims 18 to 20.

16. 22. A method of treating a bacterial infection of a non-human animal which comprises administering an effective amount of a compound as claimed in claim 1.

17. 23. A pharmaceutical composition comprising a compound of formula I 15 as defined in claim 1, or a non-toxic, pharmaceutically acceptable salt thereof, and a pharmaceutical carrier.