GB2041923A - Cephalosporin analogs and methods for production thereof - Google Patents

Abstract

Novel halogenated cephalosporin derivatives having the formula <IMAGE> where X is amino, azido or protected amino, R is carboxyl or protected carboxyl, and Hal is halogen, and salts thereof, are prepared by addition of a thiol or selenol to a starting material of the formula <IMAGE> where X1 is azido or protected amino; oxidising the adduct to give <IMAGE> where Y is Se or S; halogenating and eliminating HO-Y-R' to give the halogenated cephalosporin products. The free amino derivatives (X=NH2) and free carboxyl derivatives (R=COOH) are obtained by removal of the protecting groups.

Description

SPECIFICATION Cephalosporin analogs and methods for production thereof The present invention relates to novel cephalosporin analogs and more specifically to new carbacephem compounds which differ from the cephalosporins by having a carbon atom instead of a sulphur atom in the dihydrothiazine ring. in the Journal of the American Chemical Society, 96, 7584 (1974) and J. Med. Chem., 20, 551 (1977) certain carbacephems with substituted methyl groups at the C-3 position such as (+)-1 -carbacephalotin represented by the formula:

are disclosed as having antibacterial activity In addition some compounds which are encompassed in the definition of the present carbacephem compounds hereinafter described are named as starting materials in U.S. Patent No. 4,123,528 issued October 31, 1978.There is, however, no physical data regarding these compounds given in this patent. Nevertheless as microorganism populations develop immunity to existing antibiotics new antibacterial compounds are in demand. To this end, novel carbacephems witha hydrogen atom at the C-3 position have been synthesized which are useful as intermediates in the preparation of unexpectedly high antibacterial compounds, and such compounds as well as methods for synthesis thereof are disclosed in German Offenlegungsschrift Nos. 291 1786 and 2911787/1979.

It has now been found that novel carbacephems with a halogen atom at the C-3 position may be synthesized which are also useful as intermediates in the preparation of unexpectedly high antibacterial compounds.

In accordance with the present invention, novel carbacephem compounds, i.e. cephalosporin analogs, are synthesized. The numbering system shown in the following formula is used hereinafter.

Broadly, the present invention relates to cephalosporin analogs represented by the formula [I]:

wherein X represents an amino group, an azido group or a protected amino group, Hal represents a halogen atom and R represents a carboxyl group or a protected carboxy group. (Hereinafter compounds represented by the foregoing formula are sometimes referred to as Compound [I]. This also applies to other formulae).

More specifically, the present invention relates to novel cephalosporin analogs represented by the general formula [1-1]:

wherein Hal and R have the same meaning as defined above; and also compounds represented by the general formula [1-2]:

wherein X1 represents an azido group or a protected amino group and Hal and R have the same meaning as defined above; and the salts thereof.

As the protecting groups for the "protected amino group" in X or X1, a phthaloyl group, t butyloxycarbonyl group, 2,2,2-trichloroethyloxycarbonyl group, 2,2,2-trifl uoroethyloxycarbonyl group, benzyloxycarbonyl group, p-nitrobenzyloxycarbonyl group, p-methoxybenzyloxycarbonyl group, phenylacetyl group, phenoxyacetyl group, benzylidene group, salicylidene group and the like may be used.

Chlorine, bromine and iodine atoms are suitable as the halogen atom.

The "protected carboxyl group" in R is represented by -COOR2 wherein R2 is a protecting group of a carboxyl group used usually in the synthesis of penicillins and cephalosporins. As R2, an alkyl group having 1-5 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, etc., a halogenated alkyl group having 1 to 5 carbon atoms such as a chloromethyl group, 2,2,2-trichloroethyl group, 2,2,2-trifluoroethyl group, etc., an arylmethyl group having 7-20 carbon atoms such as a benzyl group, diphenylmethyl group, triphenylmethyl group, etc., an aryimethyl group having 8 to 20 carbon atoms and methoxy, nitro group(s), etc. on the phenvi ring.

such as p-nitrophenylmethyl group, p-methoxyphenylmethyl group, etc., a substituted silyl group such as a trimethylsilyl group, triphenylsilyl group, etc., a group enzymatically or non-enzymatically readily eliminable in vivo such as

(wherein R3 represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms, and R4 represents a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms or a phenyl group), etc. may be used.

As the salts of Compound [I], salts of an inorganic acid such as hydrochloride, sulfate, phosphate, carbonate, etc., salts of an organic acid such as formate, acetate, trifluoroacetate, malate, tartarate, etc., and when R is a carboxyl group, salts with an inorganic base such as sodium salt, potassium salt, calcium salt, barium salt, etc. and salts with an organic base such as salt with triethylamine, etc. are appropriate.

Compound [I] includes all the stereoisomers at 6- and 7-positions. A compound obtained by converting X in the general formula [I] of a cis isomer to an acylamino group exhibits stronger antibacterial activity than that obtained in the same manner as above from the corresponding trans isomer. Therefore, cis isomers which may be converted into more useful antibiotics are applicable.

Nevertheless, trans isomers are also useful as they may be converted into useful antibiotics by introducing an methoxy group at the 7-position.

Compounds [í-1 ] wherein X in Compound [I] is an amino group may be prepared from Compounds [1-2-2] set forth below wherein X1 in Compound [1-2] is an azido group or phthaloylamino group according to the following reaction process I.

Reaction Process I

wherein Xia represents an azido group or phthaloylamino group and R and Hal have the same meaning as defined above.

The reduction of Compound [1-2-2] wherein Xa is an azido group is carried out using conventional methods employed in the field of synthetic chemistry of penicillins or cephalosporins. In the reaction, Compound [1-1] can be produced by selecting suitable conditions and reagents to avoid the decomposition of substituents or functional groups of the carbacephem molecule.

Suitable reduction methods include: 1) catalytic reduction; 2) reduction musing hydrogen sulfide and a base: 3) reduction using sodium borohydride; 4) reduction using zinc-acid; and 5) reduction using chromous (II) chloride, as are set forth below.

1) Catalytic reduction Compound [1-2-] is subjected to catalytic reduction in a stream of hydrogen gas in the presence of a catalyst in an inactive solvent to obtain Compound [1-1]. Any solvent which does not affect the reaction may be used. Preferably ethanol, water, tetrahydrofuran, dioxane, ethyl acetate, acetic acid, or a mixture thereof is employed. As the catalyst, palladium-carbon, platinum oxide, palladium-calcium carbonate and Raney nickel are appropriate.

The reaction is generally carried out at a temperature of-20 to 1000C,preferaby at room temperature, and at a pressure of 1 to 50 atmospheres, preferably at atmospheric pressure.

In this reaction, when a compound represented by the general formula [1-2-2] wherein R is a carboxyl group protected by a protecting group such as a substituted arylmethyl group, for example, a benzyl group, paramethoxybenzyl group, paranitrobenzyl group, benzhydryl group, trityl group, etc. is used as the starting material, a compound represented by the general formula [1-1] wherein R is a carboxyl group may also be obtained.

2) Reduction using hydrogen sulfide-base Compound [1-2-2] is reduced with hydrogen sulfide in the presence of a base in an inactive solvent to obtain Compound [1-1]. As the solvent, methylene chloride, chloroform, benzene, tetrahydrofuran, and the like are used alone or in combination. As the base, triethylamine, pyridine, and the like are appropriate.

The reaction is carried out at a temperature of O to 500C, preferably at room temperature.

3) Reduction using sodium borohydride Compound i1-2-2] is reduced with sodium borohydride in an inactive solvent to obtain Compound [1-1]. As the solvent, methanol, ethanol, dioxane, tetrahydrofuran are used alone or in combination.

Sodium borohydride is used in an amount of one equivalent or excess to Compound [1-2-2].

The reaction is carried out at a temperature of O to 1 000C, preferably 10 to 500 C.

4) Reduction using zinc-acid Compound [1-2-2] is reduced with zinc-acid in an inactive solvent to obtain Compound [1-1]. As the solvent, acetone, water, dioxane, tetrahydrofuran, ethanol, acetic acid, etc. are used alone or in combination. As the acid, hydrochloric acid or acetic acid is suitable. Zinc and the acid are used in an amount of one equivalent or excess to Compound [1-2-2].

The reaction is carried out at a temperature of O to 1 000C, usually room temperature to 600 C.

5) Reduction using chromous (II) chloride Compound [1-2-2] is reduced with chromous (II) chloride in the presence of an acid in an inactive solvent. The acid, solvents, and reaction conditions are the same as in zinc-acid method.

The elimination of a phthaloyl group from Compound [1-212] is carried out according to a conventional method for elimination of a phthaloyl group. As agents for the elimination, hydrazine, hydroxylamine, ethylamine, dimethylaminopropylamine, sodium sulfide-methylhydrazine, etc. may be used. The reaction may be carried out at -20 to 300C in an alcohol such as methanol, ethanol, and the like but other conventional conditions may also be applicable.

Compound [1-2] is prepared from compounds represented by the general formula [Il].

wherein X1, Hal and R have the same meaning as defined above, Y represents a sulfur atom or selenium atom, and Ri represents a substituted or unsubstituted alkyl group, aralkyl group or aryl group, or a heterocyclic group according to the following reaction process II.

Reaction Process II

This reaction is the elimination of R1-Y-OH and is carried out usually in a solvent. The reaction temperature is O to 2000 C. As solvents preferably used, inert solvents such as aliphatic hydrocarbon (hexane, heptane, etc.), halogenated hydrocarbon (chloroform, methylene chloride, carbon tetrachloride, etc.), aromatic hydrocarbon (benzene, toluene, xylene, etc.), ether (diethyl ether, tetrahydrofuran, dimethoxyethane, etc.), ester (ethyl acetate, etc.), amide (dimethylformamide, dimethylacetamide, etc.), sulfoxide (dimethylsulfoxide, etc.) and so on may be used.

In the case of the sulfoxide (Y = S), the reaction proceeds with heating. Reaction temperature is preferably 50 to 2000 C. In case of elimination of a phenylsulfinyl group, most preferable results are obtained by heating with reflux temperature.

In case of the selenoxide (Y = Se), the reaction proceeds at a lower temperature compared with the case of the sulfoxide, and is preferably 0 to 300C.

In the definition of R' in the general formula (II), as an alkyl group, an alkyl group having 1 to 5 carbon atoms such as a methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl group, etc.; as an aralkyl group, a phenyl-alkyl group having 7 to 20 carbon atoms such as a benzyl, phenethyl group, etc.; and as an aryl group, a phenyl group are illustrative. As the substituent(s) of the alkyl, aralkyl or aryl group, a halogen atom such as chlorine, bromine, etc., a nitro group, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms are illustrative. Furthermore, as the heterocyclic group, a tetrazolyl group or thiaziazolyl group are illustrative.

Preferably, a phenyl group as R1, a sulfur atom as Y and a chlorine atom as Hal are used.

Compound (II) includes all the stereoisomers at 2-, 3-, 6- and 7-positions and mixtures thereof.

Compound [II] wherein the 6- and 7-positions are cis configuration is more useful as a starting compound for the more useful Compound [I] in cis configuration. Nevertheless, Compound [II] with trans configuration is useful as a starting compound of Compound [I] with trans configuration.

Compound [II] is also a new compound and is prepared from a compound represented by the aeneral formula [1111:

wherein X1,Y, R1 and R have the same meaning as defined above according to reaction process ill.

Reaction Process Ill

This reaction is an introduction of a halogen atom in carbon of the sulfinyl or seleninyl group. For example, for a-chlorination of the sulfoxide, the reaction is carried out using a halogenating agent such as tosyl chloride, nitrosyl chloride, dichloroiodophenyl, t-butyl hypochlorite, sulfuryl chloride, most preferably sulfuryl chloride, if necessary in the presence of a base such as piridine, or the like.

The reaction is carried out at -78 to 200 C, preferably under cooling conditions in an inert solvent, without water. The reaction time is usually within 30 minutes. As an example of a preferred embodiment, the reaction proceeds very mildly and rapidly by using sulfuryl chloride as a halogenating agent and a halogenated hydrocarbon such as dichloromethane as a solvent to obtain the desired compound in good yield.

Addition of calcium oxide to the reaction system for catching hydrogen chloride formed according to the progress of the reaction sometimes results in good effect. When an excess amount of sulfuryl chloride is used, dichloro compounds sometimes are formed as by-products. The reaction of alkylphenyl sulfoxide or dialkyl sulfoxide with sulfuryl chloride has been reported [K.C. Tin et. al. Tetrahedron-letter, 4643 (1970)] but there has been no report on such reaction applied to a p-lactam compound.

Compound [111] is also a new compound and is prepared from a compound represented by the general formula [IV]:

wherein XJ, Y, R and R1 have the same meaning as defined above according to reaction process IV.

Reaction Process IV

This reaction is an oxidation reaction of sulfide or selenide, and conventional oxidation reactions of such compounds to a sulfinyl compound or seleninyl compound are applicable. As oxidizing agents, various oxidizing agents such as manganese dioxide, chromic acid, lead tetraacetate, ruthenium tetroxide, N-halocarbonamide, oxygen, ozone, and the like may be used. As especially preferable oxidizing agents, anodic oxidation, periodic acid, hydrogen peroxide, organic peracid such as m-chloroperbenzoic acid are used.

The solvent is selected according to the oxidizing agent. Water, alcohol, acetic acid and a mixture thereof, or a halogenated hydrocarbon such as chloroform, and the like are preferred.

The reaction is usually carried out at -50 to 1 000C. when an excess amount of the oxidizing agent is used and the temperature is raised, sulfone is sometimes formed.

Compound [IV} is a new compound and is prepared from a compound represented by the general formula IVI:

wherein X1 and R have the same meaning as defined above according to reaction process V.

Reaction Process V

This reaction is the addition reaction of thiol or selenol represented by R1-V-H. The reaction is usually carried out at -50 to 1 000C in a solvent, and if necessary in the presence of a base.

As the base, organic bases such as piperidine, diethylamine, triethylamine, etc., metal hydride such as sodium hydride, potassium hydride, etc., alkyllithium such as n-butyllithium, etc., sodium hydroxide, potassium hydroxide, etc. may be used. When a strong base is used it is preferred, for avoiding cleavage of the /3-lactam ring, that the compound R1-Y-H is first treated with one or less equivalent amount of the base and then reacted with Compound V. More preferable results are obtained with the use of a weak base than with the use of a strong base. For example, better results are obtained with the use of piperidine when thiophenol is used as R1-V-H.

As a solvent, solvents inactive to the addition reaction are used. Aromatic hydrocarbons such as benzene, toluene, xylene, etc., halogenated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, ethers such as ethyl ether, tetrahydrofuran, dimethoxyethane, etc., esters such as ethyl acetate, etc., alcohols such as methanol, ethanol, etc., amides such as dimethylformamide, dimethylacetamide, etc., sulfoxides such as dimethylsulfoxide, etc., acetonitrile and so on are employed.

Compound [I] wherein R is a carboxyl group, may be produced by the following reaction process VI using a compound represented by the general formula [1-3] as the starting compound.

Reaction Process VI

In the compounds of the foregoing reaction, X, Hal and R2 have the same meaning as defined above.

The reaction can be carried out by conventional means employed in the field of the synthetic chemistry of penicillins or cephalosporins. In the reaction, Compound [1-4] can be produced by selecting suitable conditions and reagents to avoid the decomposition of substituents or functional groups of the carbacephem molecule.

Suitable reactions which convert theCOOR2 group to a -COOH group include: 1) catalytic reduction; 2) acidolysis; 3) cleavage reaction using a Lewis acid; 4) hydrolysis; 5) reduction other than catalytic reduction using reducing agents; and 6) a method using an esterase; each of which are described below.

1) Catalytic reduction In this reaction, the COOR2 group is converted to a COOH group in the presence of a catalyst in a hydrogen atmosphere and inactive solvent. As the solvent, any solvent which does not affect the reaction, and preferably ethanol, water, tetrahydrofuran, dioxane, ethyl acetate and acetic acid, may be used alone or in combination. As the catalyst, palladium-carbon, platinum oxide, pailadium-calcium carbonate and Raney nickel are suitable. The reaction is generally carried out at a pressure of 1 to 50 atmospheres and a temperature of O to 1 000C, preferably at atmospheric pressure and room temperature.

This method is preferably employed when R2 is a benzyl group, p-nitrobenzyl group, diphenylmethyl group, triphenylmethyl, p-methoxybenzyl group or the like.

When X is an azido group, the azido group may be reduced to an amino group when R2is converted to H by catalytic reduction. The resulting compound having an amino group is also a desired compound of the present invention.

2) Acidolysis In this reaction, the COOR2 group is converted to a COOH group with an acid in an inactive solvent.

As the acid, hydrogen chloride, p-toluenesulfonic acid, trifluoroacetic acid, etc. are suitable. As the solvent, any solvent which does not affect the reaction, and preferably ethyl acetate, benzene, ethanol, acetic acid, dioxane, methylene chloride and chloroform, may be used alone or in combination.

The reaction is generally carried out at a temperature of -1 5 to 500C, preferably 0 to 250C, for 10 minutes to 5 hours, preferably 30 minutes to 3 hours.

This method is preferably used when R2 is a t-butyl group, trityl group and so on.

3) Cleavage reaction using a Lewis acid In this reaction, the COOR2 group is converted to a COOH group by cleavage in the presence of a Lewis acid in an inactive solvent such as any solvent which does not affect the reaction, preferably a mixture of a nitroalkane such as nitromethane and a haloalkane such as methylene chloride. As the Lewis acid, aluminum chloride, boron trifluoride, titanium tetrachloride, tin tetrachloride, and the like are used. The acid is used in an amount of 1.0 to 1.5 molar equivalents to Compound [1-3]. The reaction is preferably carried out in the presence of an agent such as anisole which uptakes any carbonium cation possibly formed. The reaction is carried out at a temperature of O to 500C, preferably at room temperature for 1 to 10 hours.

Addition of thiol compound such as ethanethiol, ethanedithiol, etc. often enhances this type of reduction.

This method is preferably used when R2 is a benzyl, p-nitrobenzyl group and so on.

4) Hydrolysis In this reaction, the COOR2 group is converted to a COOH group by hydrolysis in the presence of an acid or alkali in an inactive solvent. Suitable acids include p-toluenesulfonic acid, hydrochloric acid, acetic acid, and the like. Any solvent which does not affect the reaction may be used and preferably aqueous methanol, N,N-dimethylformamide, acetic acid-water-tetrahydrofuran are employed. The reaction is generally carried out at a temperature of O to 500 C, preferably 1 5 to 250C for 90 minutes to 2 hours.

This method utilizing an acid is preferably used when R2 is a t-butyldimethylsilyl group.

As an alkali, calcium carbonate is preferably used in an amount of 1 to 6 molar equivalents to Compound [1-3]; and any solvent which does not affect the rection and preferably tetrahydrofuranwater, dioxane-water or acetone-water are used. The reaction is generally carried out at a temperature of O to 300C for 30 minutes to 24 hours.

This method utilizing an alkali is preferably employed when R2 is a methyl group, ethyl group and so on.

5) Reduction using reducing agents (other than catalytic reduction) In this reaction, the COOR2 is converted to a COOH by reduction in an inactive solvent, for example using a zinc-acid method. For this reaction a solvent such as acetone, water, dioxane, tetrahydrofuran, ethanol, acetonitriie, N,N-dimethylformamide and acetic acid may be used alone or in combination. As the acid, hydrochloric acid and acetic acid are suitable. The reaction is carried out at a temperature of O to 1 OO0C, preferably 0 to 400C for 1 to 10 hours. The amount of zinc used for the reaction is usually 1 to 10 molar equivalents.

This method is preferably employed when R2 is 2,2,2-trichloroethyl and so on.

Compound [V] used as a starting material and the processes for preparation thereof are disclosed in German Offenlegungsschrift No. 2911786/1979. A representative example of the process steps is set forth below.

For further reference, preparation of cephalosporins having a halogen substituent at the 3-position is carried out by the following reaction steps. [G.V. Kaiser, et. al., J.O. Chem., 35, 2430 (1970), R.R.

Chauvette et. al., J. Am. Chem. Soc., 96, 4986 (1974)1.

As apparent from the foregoing, the process of the present invention is carried out according to 4 steps, i.e., 1) addition of thiol or selenol, 2) oxidation, 3) halogenation and 4) elimination reaction; and, if necessary, additional steps such as 5) conversion of an azido or phthaloylamino group to an amino group at the 7-position and/or 6) conversion of a protected carboxyl group to a carboxyl group at the 2position, using a 3H-carbacephem compound (for example, Compound 5) as the starting compound.

Thus, the present invention offers new and useful 3-halogensubstituted carbacephem structures and new processes for preparation thereof quite different from prior processes for the preparation of cephalosporin analogs.

Certain specific embodiments of the invention are illustrated by the following represented examples.

EXAMPLE 1 Preparation of ()-cis-7-azido-3-chloro-2-t-butyloxycarbonyl- 1 -azabicyclo[4,2,010ct-2-en-8-one:

In this example, the compound is prepared according to the following processes a), b), c) and d). Cis means the stereoisomerism at the 3- or 4-position of the 2-azetidinone ring or at the 6- or 7position of the 1-azabicyclo[4,2,0] octane ring, which designation is applied as well hereinafter.

a) Preparation of ()-cis-7-azido-3-phenylthio-2-t-butyloxycarbonyl-1-azabicyclo[4,2,0]octane-8-one:

In this step, 528 mg (2 m mole) of ()-cis-7-azido-2-t-butyloxycarbonyl-1 -azabicyclo[4,2,0]oct-2en-8-one is dissolved in 1 5 ml of anhydrous benzene. Then, 0.2 ml (2 m mole) of thiophenol and 0.2 ml (2 m mole) of piperidine are added to the solution and the mixture is stirred at room temperature for 2 hours. After the reaction, the reaction mixture is washed with 10% citric acid and saturated aqueous sodium chloride, and dried with anhydrous sodium sulfate.The solvent is distilled off under reduced pressure and the resultant oily residue is purified by silica gel column chromatography [silica gel: Wako gel R, , C-200, product of Wako Junyaku Co., Ltd. (the same silica gel is used hereinafter), eluent: ethyl acetate: n-hexane = 1:4 (in volume, the same hereinafter)] to obtain 720 mg (yield: 96.3%) of the desired compound having the following physical properties.

Melting point: 77.5-78.00C IR(KBr)P cm 2110,1765, 1745 max NMR(CDC13) gs (ppm): 7.28-7.60(5H,m), 4.78(1 H,d, J = 5 Hz), 4.33(1 H,s), 3.78-3.98(1 H,m), 3.81(1 H,s), 1 .50-2.34(4H,m), 1 .42(9H,s) b) P reparation of ()-cis-7-azido-3-phenylsulfinyl-2-t-butyloxyca rbonyl- 1 -azabicyclo[4,2,0]octane- 8-one:

In this step, 480 mg (1.28 m mole) of the 3-phenylthio compound obtained in the foregoing step a) is dissolved in 50 ml of anhydrous chloroform. Then 240 mg (1.41 m mole) of m-chloroperbenzoic acid is added to the solution under ice cooling.The reaction is carried out with stirring for 30 minutes and the reaction mixture is washed with saturated aqueous sodium bicarbonate and saturated aqueous sodium chloride and dried with anhydrous sodium sulfate. The solvent is distilled off under reduced pressure to obtain 500 mg (99.9%) of the desired compound having the following physical properties.

Melting point: 95.5-96.50C -1 IR(KBr)v max : 2120,2100,1780,1735, 1035 NMR(CDCI3) a (ppm): 7.55-7.91 (5H,m), 4.87(1 H,d, J = 4.6Hz), 4.05(1 H,s), 3.90-4.10(1 H,m), 3.10(1 H,s), 1 .70-2.84(4H,m), 1 .30(9H,s) c) Preparation of (+)-cis-7-azido-3-chlorn-3-phenylsulfinyl-2-t-butyloxycarbonyl- 1 - azabicyclo[4,2,0]octane-8-one:

In this step, 109 mg of the sulfoxide compound obtained in the preceding step b) is dissolved in 1 ml of methylene chloride. Then, 23.5 mg (0.42 m mole) of calcium oxide is added to the solution.

Thereafter, 27 yl (0.34 m mole) of sulfinyl chloride is added to the mixture under ice cooling. The reaction is carried out with stirring under ice cooling for one hour.

The reaction mixture is then washed with 10% citric acid, saturated aqueous sodium bicarbonate and saturated aqueous sodium chloride and dried with anhydrous sodium sulfate. The solvent is distilled off under reduced pressure and the resultant oily residue is purified by silica gel chromatography (silica gel; 5 g, eluent; ethyl acetate: n-hexane = 1:5) to obtain 66.5 mg (56.19/0) of the desired compound as a oily product having the following properties.

IR(CHCI3) p cm-l: 2120,1770,1735,1055 max NMR(CDCI3) a (ppm): 7.53-8.00(5H,m), 4.90(1 H,d, J = 5Hz), 4.43(1 H,s), 4.15-4.35(1 H,m), 1.83-2.85(1 H,m), 1 .38(9H,s) d) Preparation of (~)-cis-7-azido-3-chloro-2-t-butyloxycarbonyl- 1 -azabicyclo[4,2,0]oct-2-en-8-one:

In this step, 1.3 g (3.06 m mole) of the 3-chloro-3-phenylsulfinyl compound obtained in the same manner as described in the preeding step c) is dissolved in 100 ml of carbon tetrachloride and the solution is refluxed with heating for 6 hours.

After the reaction is completed, the solvent is distilled off under reduced pressure, and the resultant residue is purified by silica gel chromatography (silica gel; 100 g eluent; ethyl acetate: hexane = 1:5) to obtain 596 mg (65.2%) of the desired compound having the following physical properties.

Melting point: 96-970C IR(KBr)v cm : 2120, 1765, cm1 max 2120,1765,1735,1630 PMR(CDCI3) 8(ppm): 4.93(1 H,d, J = 5Hz), 3.72-3.92(1 H,m), 2.56-2.70(2H,m),1.86-2.32(2H,m),1.55(9H,S) CMR(CDCI3)8(ppm): 127.7,125.0 EXAMPLE 2 Preparation of (+)-cis-7-a mino-3-chloro-2-t-butyloxycarbonyl- 1 -azabicyclo[4,2,0]oct-2-en-8-one:

In this example, 350 mg (1.17 m mole) of the azido compound obtained in step d) of Example 1 is dissolved in 20 ml of ethanol. Then, 1.2 ml of 1 N hydrochloric acid and 70 mg of 10% palladiumcarbon are added to the solution. Hydrogen gas is introduced into the mixture at room temperature and at atmospheric pressure for 3 hours.The palladium-carbon is then filtered off and the filtrate is concentrated under reduced pressure. The resultant solid is dissolved in water and the solution is washed with ether. The water layer is rendered weakly alkaline by adding sodium bicarbonate and is then extracted with ethyl acetate. The ethyl acetate layer is washed with saturated aqueous sodium chloride and dried with anhydrous sodium sulfate. The solvent is thoroughly distilled off under reduced pressure to obtain 218.4 mg (68.4%) of the desired compound as a powder having the following properties.

Melting point: 102.5-1 04.50C IR(KBr)v cm : 1770,1720,1620 max NMR(CDCI3) 8 (ppm): 4.43(1 H,d, J = 5Hz), 3.52-3.90(1 H,m), 2.52--2.72(2H,m), 2.22(2H,br), 1.82-2.1 7(2H,m), 1 .55(9H,s) EXAMPLE 3 Preparation of trifluoroacetate of ()-cis-7-amino-3-chloro-1-azabicyclo[4,2,0]oct-2-en-8-on-2- carboxylic acid:

In this example, 1 ml of trifluoroacetic acid is added to 102.2 mg (0.31 m mole) of the aminoester compound obtained in Example 2 under ice cooling and the mixture is stirred at room temperature for 30 minutes.

The solvent is distilled off under reduced pressure and ether is added to the resultant oily residue to render it powdery. The residue is collected by suction filtration and dried in vacuo to obtain 75.5 mg (60.9%) of the desired compound having the following properties.

Melting point: 208-2200C (decomposition) IR(KBr)v cma : 1795, 1630 EXAMPLE 4 Preparation of (+)-cis-7-azido-3-chloro-1-azabicyclo[4,2,0]oct-2-en-8-on-2-carboxylic acid:

In this example, 2 ml of trifluoroacetic acid is added to 83.9 mg (0.28 m mole) of the azido-ester compound obtained in step d) of Example 1 and the mixture is stirred at room temperature for 30 minutes.

The solvent is distilled off under reduced pressure and ether is added to the resultant oily residue to render it powdery. The residue is collected by suction filtration and dried in vacuo to obtain 25.0 mg (36.7%) of the desired compound having the following properties.

Melting point: 147.5-148.50C IR(KBr)v cm : 2130,1770,1715,1605 max NMR(CD30D) 8 (ppm): 5.16(1 H,d, J = 5Hz), 3.82-4.02(1 H,m), 2.63-2.77(2H,m), 1.73-2.21 (2H,m) In the following reference examples processes for preparing end products from the intermediates of the present invention are further illustrated.

REFERENCE EXAMPLE 1 Preparation of ()-cis-7-[2-(2-chloroacetamidothiazole-4-YI)-2-sYn-methoxyiminoacetYla mino]-3chloro- 1 -azabicyclo[4,2,0]oct-2-en-8-on-2-carboxylic acid:

In this reference example,122.6 mg (0.44 m mole) of 2-(2-chloroacetamidothiazole-4-yl)-2-synmethoxyiminoacetic acid is dissolved in 2.5 ml of anhydrous methylene chloride. Then, 68 p1 (0.49 m mole) of triethylamine is dissolved therein and 92.0 mg (0.44 m mole) of phosphorus pentachloride is added under cooling with an ice-salt bath. The mixture is stirred at that temperature for one hour after which 5 ml of n-hexane is added thereto. The mixture is stirred under ice cooling for an additional 1 5 minutes.A separated oily material is obtained by removing n-hexane by decantation.

The oily material is dissolved in 4 ml of tetrahydrofuran to prepare an acid chloride solution. In a separate vessel, 121.7 mg (0.37 m mole) of the trifluoroacetate of (+)-7-amino-3-chloro-1 azabicyclo[4,2,0]oct-2-en-8-one-2-carboxylic acid obtained in the same manner as described in Example 3 is dissolved in 5 ml of 50% aqueous tetrahydrofuran and 0.2 ml (1.47 m mole) of triethylamine. To this solution, the above-prepared acid chloride solution in tetrahydrofuran is added with stirring under ice cooling. The mixture is stirred at that temperature for one hour and adjusted to pH 3 with 1 N hydrochloric acid. Water is then added and the mixture is extracted with ethyl acetate.

The extract is washed with saturated aqueous sodium chloride and dried with anhydrous sodium sulfate. The solvent is distilled off to obtain 53.9 mg (30.5%) of the desired compound as a powder having the following properties.

IR(KBr)v mmax 1770,1680,1555,1045 NMR(DMSO-d6)8(ppm): 9.38(1 H,d, J = 8Hz), 7.37(1 H,s), 5.45(1 H,q, J = 5, 8Hz), 4.35(2H,s) REFERENCE EXAMPLE 2 Preparation of (+)-cis-7-[2-(2-aminothiazole-4-yl)-2-syn-methoxyiminoacetamido]-3-chlorn- 1 - azabicyclo[4,2,0]oct-2-en-8-on-2-carboxylic acid:

In this reference example, 51.2 mg (0.11 m mole) of the chloro-acetamido compound obtained in the foregoing Reference Example 2 is dissolved in 1 ml of dimethylacetamide and 1 6.3 mg 10.22 m mole) of thiourea is added thereto. Reaction is carried out by stirring the mixture at room temperature for 14 hours.

Then, 7 ml of ether is added to the reaction mixture and the stirring is continued for an additional 10 minutes. A separated oily material is obtained by removing the ether by decantation. The oily material is dissolved in a small amount of dimethylsulfoxide, absorbed on 10 ml of HP-10 resin in a column and eluated with dimethylsulfoxide. The eluate is twice treated with HP-1 0 resin [eluent: watermethanol (amount of methanol is gradually increased and finally elution is carried out with water: methanol = 1:1)] to obtain 15.2 mg (35.4%) of the desired compound having the following properties.

Melting point: 185.0-1 88.00C (decomposed) -1 cm IR(KBr)v max : 1765,1670,1630,1540,1040 NMR(DMSO--cl0) 8 (ppm): 9.28(1 H,d, J = 8.8Hz),7.17(2H,s), 6.75(1 H,s), 5.44(1 H,q, J = 5.3, 8.8Hz), 3.84(3H,s), 1 .24-2.52(4H,m) The antibacterial activity of the compound obtained in Reference Example 2 is set forth in the following table. The activity is determined by the Heart Infusion Agar Dilution Method (pH 7.2), and Cefazolin is used as a reference.

Compound of Reference Strain Cefazolin Example 2 Staphylococcus aureus 209-P < 0.05 50 Staphylococcus aureus Smith 0.4 50 Staphylococcus epidernidis 0.78 50 Escherichia coil NlHJC-2 1.56 0,78 Escherichia coil Juhl 1.56 0.4 Klebsiella pneumoniae 8045. 0,78 < 0.05 Klebsiella pneumoniae Y60 3.12 0.78 Serratia marcescens T-55 50 1.56 Proteus mirabilis 1287 12.5 0.1 Proteus vulgaris 6897 12.5 0.4 Proteus morgrill KY4298 > 100 0.4 Proteus rettgeri KY4289 25 0.1 Pseudomonas putida F264 > 100 3.12

Claims (42)

1. A compound of the formula:

wherein X represents an amino group, and azido group or a protected amino group, Hal represents a halogen atom and R represents a carboxyl group or a protected carboxyl group, and the salts thereof.

2. A compound according to claim 1 wherein X is a protected amino group.

3. A compound according to claim 1 wherein X is an amino group.

4. A compound according to claim 1 wherein X is an azido group.

5. A compound according to claim 2, 3 or 4, wherein the hydrogen atoms at the 6- and 7positions have cis configuration.

6. A compound according to claim 2 wherein the protecting group is selected from the group consisting of a phthaloyl group, a t-butyloxycarbonyl group, a 2,2,2-trichloroethyloxycarbonyl group, a 2,2,2-trifluoroethyloxycarbonyl group, a benzyloxycarbonyl group, a p-nitrobenzyloxycarbonyl group, a p-methoxybenzyloxycarbonyl group, a phenylacetyl group, a phenoxyacetyl group, a benzylidene group and a salicylidene group.

7. A compound according to claim 1, 2, 3 or 4 wherein Hal is a chlorine atom.

8. A compound according to claim 1 or 5 wherein R is a carboxyl group.

9. A compound according to claim 1 or 5 wherein R represents a protected carboxyl group.

represented by the general formulaCOOR2 wherein R2 represents an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, an arylmethyl group having 7 to 20 carbon atoms, an arylmethyl group having 8 to 20 carbon atoms and methoxy or nitro group(s) on the phenyl ring, a substituted silyl group, or a group enzymatically or non-enzymatically readily eliminable in vivo.

10. A compound according to claim 9 wherein R2 represents a t-butyl group, a benzyl group, a diphenylmetyl group, a triphenylmethyl group, a p-nitrophenylmethyl group or a p-methoxyphenyl group.

11. cis-7-azido-3-chloro-2-t-butyloxycarbonyl-1-azabicyclo[4,2,0]oct-2-en-8-one.

12. cis-7-amino-3-chloro-2-t-butyloxycarbonyl-1 -azabicyclo[4,2,0]oct-2-en-8-one.

13. cis-7-amino-3-chloro-1 -azabicyclo[4,2,0)oct-2-n-8-on-2-carboxylic acid.

14. cis-7-azido-3-chloro-1 -azabicyclo[4,2,0]oct-2-en-8-on-2-carboxylic acid.

15. A process for producing a compound of the formula

wherein Hal represents a halogen atom and R represents a carboxyl group or a protected carboxyl group which comprises converting the Xia group of a compound represented by the formula:

wherein Xia represents an azido group or a phthaloylamino group, and Hal and R have the same meaning as defined above to an amino group.

16. A process according to claim 1 5 wherein said protected carboxyl group is represented by the general formulaCOOR2 wherein R2 represents an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, an arylmethyl group having 7 to 20 carbon atoms, an arylmethyl group having 8 to 20 carbon atoms and methoxy or nitro group(s) on the phenyl ring, a substituted silyl group, or a group enzymatically or nonenzylmatically readily eliminable in vivo.

17. A process according to claim 16 wherein R2-represents a t-butyl group, a benzyl group, a diphenylmethyl group, a p-nitrophenylmethyl group or a p-methoxyphenylmethyl group.

1 8. A process according to claim 1 5 wherein Xia is an azido group and the conversion is carried out by reduction.

19. A process according to claim 1 8 wherein the reduction is a catalytic reduction.

20. A process according to claim 1 8 wherein hydrogen sulfide and a base are used as a reducing agent in the reduction.

21. A process according to claim 1 8 wherein sodium borohydride is used in the reduction.

22. A process according to claim 18 wherein zinc and an acid are used in the reduction.

23. A process according to claim 1 8 wherein the reduction is carried out with chromous (II) chloride in the presence of an acid.

24. A process according to claim 19 wherein R in the starting compound is a protected carboxyl group and the protected group is converted to a carboxyl group.

25. A process according to claim 24 wherein said protected group is a benzyl group, a pmethoxybenzyl group, a p-nitrobenzyl group, a benzhydryl group or a trityl group.

26. A process according to claim 1 5 wherein Hal is a chlorine atom.

27. A process according to claim 26 wherein R is a t-butyloxycarbonyl group.

28. A process according to claim 26 wherein R is a carboxyl group.

29. A process for producing a compound of the formula:

wherein X1 represents an azido group or a protected amino group, Hal represents a halogen atom, and R represents a carboxyl group or a protected carboxyl group, which comprises eliminating R1-Y-OH from a compound represented by the formula:

wherein Y represents a sulfur atom or a selenium atom and R' is a substituted or unsubstituted alkyl, aralkyl or aryl group or a heterocyclic group or a heterocyclic group and X1, Hal and R have the same meaning as defined above.

30. A process according to claim 29 wherein X is a protected amino group whose protecting group is selected from the group consisting of a phthaloyl group, a t-butyloxycarbonyl group, a 2,2,2 trichloroethyloxycarbonyl group, a 2,2,2-trifluoroethyloxycarbonyl group, a benzylocycarbonyl group, a p-nitrobenzyloxycarbonyl group, a p-methoxybenzyloxycarbonyl group, a phenylacetyl group, a phenoxyacetyl group, a benzylidene group and a salicylidene group.

31. A process according to claim 29 wherein R is a protected carboxyl group represented by the general formula QOoR2 wherein R2 represents an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, an arylmethyl group having 7 to 20 carbon atoms, an arylmethyl group having 8 to 20 carbon atoms and methoxy or nitro groups on the phenyl ring, a substituted silyl, or a group enzymatically or non-enzymatically readily eliminable in vivo.

32. A process according to claim 31 wherein R2 represents a t-butyl group, a benzyl group, a diphenylmethyl group, a p-nitrophenylmethyl group or a p-methoxyphenylmethyl group.

33. A process according to claim 29 wherein said aryl group in R' is a phenyl group.

34. A process according to claim 29, wherein the elimination reaction is carried out at O to 2000C in a inactive solvent.

35. A process according to claim 34 wherein the elimination reaction is carried out by refluxing in carbon tetrachloride.

36. A process according to claim 29, wherein X, is an azido group, Hal is a chlorine atom and R is a t-butyloxycarbonyl group.

37. A process according to claim 36 wherein Y is a sulfur atom and R1 is a phenyl group in the starting compound.

38. A process for producing a compound of the formula:

wherein X represents an amino group, an azido group or a protected amino group and Hal represents a halogen atom, which comprises converting the COOR2 group of a compound represented by the general formula:

wherein R2 represents an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atom, an arylmethyl group having 7 to 20 carbon atoms, an arylmethyl group having 8 to 20 carbon atoms and methoxy or nitro group(s) on the phenyl ring, a substituted silyl group, or a group enzymatically or nonenzymatically readily eliminable in vivo, and X and Hal have the same significance as defined above to a -COOH group.

39. A process according to claim 38 wherein R2 represents a t-butyl group, a benzyl group, a diphenylmethyl group, a p-nitrophenylmethyl group or a p-methoxyphenylmethyl group.

40. A process according to claim 38, wherein the conversion is carried out by catalytic reduction.

41. The process according to claim 38, wherein the conversion is carried out bv acidolvsis.

42. A process according to claim 1 5, 29 or 38 wherein the hydrogen atoms at the 6- and 7positions have cis configuration.