GB1602876A - Method for producing cepham compounds - Google Patents

Description

(54) METHOD FOR PRODUCING CEPHEM COMPOUNDS (71) We, TAKEDA YAKUHIN KOGYO KABUSHIKI KAISHA also known as TAKEDA CHEMICAL INDUSTRIES LTD., ajoint stock company organised under the laws of Japan of 27 Doshomachi 2-chome, Higashi-ku, Osaka, Japan do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a method of producing cephem compounds.

More particularly, the present invention relates to a method of producing a cephem compound of the formula (I):

wherein R2 is hydrogen or an ester residue, or a salt thereof, which comprises silylating a compound of the formula (II):

wherein R'CO is an acyl group, and R2 has the same meaning as defined above, or a salt thereof, with a silylating agent to produce a compound silylated at the carbamoyl group of the 3 position: reacting the silylated compound with a halogenating agent to produce the corresponding iminohalide compound; reacting the iminohalide compound with a C14 aliphatic alcohol to produce the corresponding iminoether compound; and subyecting the iminoether compound to solvolysis.

The above end-products, particularly 7 - amino - 3 - carbamoyloxymethyl 3 - cephem - 4 - carboxylic acid (i.e. the compound (I) wherein R2 is hydrogen, hereinafter sometimes referred to briefly as 7-ACC) are important intermediates for the production of cephalosporin antibiotics having a carbamoyloxymethyl group in the 3-position. Various methods for producing 7-ACC have been reported.

For example, the laid-open specification of Japanese Patent Application No.

32829/1973 teaches a method for producing 7-ACC using 7-aminocephalosporanic acid (hereinafter referred to briefly as 7-ACA) as the starting material. This method, however, is not commercially advantageous in that it involves a large number of production steps, employs a costly starting material (7-ACA) and involves a step of esterase hydrolysis. Meanwhile, we thought that the method of producing 7-ACC from 7 - (D - 5 - amino - 5 - carboxyvaleramido)- 3 hydroxymethyl - 3 - cephem - 4 - carboxylic acid (deacetyl-cephalosporin C, hereinafter sometimes referred to briefly as DCPC), which is produced directly by fermentation in high yield and at low-production cost (Nature New Biology 246.

154 (1973), Japanese Patent Application laid-open to the public No. 491/1974), was commercially the most desirable method for the purpose. However, this method is still not satisfactory. Thus, in this method, the 3-hydroxymethyl group is first converted to a carbamoyloxymethyl group and, then, the 7-acylamide group must be cleaved off to yield 7-ACC but, in the latter reaction, the carbamoyl group reacts with the phosphorus pentachloride reagent used for the cleavage as shown below to preclude attainment of a satisfactory result (see Tetrahedron Letters 1976, 2401).

RCONH S 120, II PC15/Py | \ o COUCH2 COOCH2 Methanol WCH2C I ;H2 PCl5 20H OCNHP (OCH 3 CoOCH f 2 COUCH 02 COUCH 02 (RCO=acyl; O=phenyl; and Py=pyridine).

We studied the above problem and found by N.M.R. spectrometry that the carbamoyl group in the 3-position of the cephalosporin nucleus is readily silylated by an appropriate silylating agent, and that the silylated carbamoyl group resists the attack of the halogenating agent, e.g. the phosphorus pentachloride. Further research based on the above findings led us to the finding that compounds of the general formula (I) including 7-ACC can be produced from DCPC as the starting material with advantage and on a commercial scale.

These findings were followed by further research which has resulted in the perfection of this invention.

In the above general formulae, the acyl group R1CO may be any of the acyl groups thus far known in the art of penicillins and cephalosporins. We prefer, for example, 5 - amino - 5 - carboxyvaleryl, phenylacetyl and phenoxyacetyl. The most desirable are acyl groups of the formula:

(wherein R3 is a protected amino group).

In the above formulae, the protective group on the protected amino R3 may be any of the protective groups which are known per se in the art of cephalosporins, for example, phthaloyl, naphthoyl, benzoyl, benzoyl substituted by nitro, halogen or lower alkyl (C,~4) (e.g. chlorobenzoyl, p-nitrobenzoyl, toluoyl or p - tert benzoyl), benzenesulfonyl, benzenesulfonyl substituted by lower alkyl (C1~4) (e.g.

p - tert - butylbenzenesulfonyl or toluenesulfonyl), aryl-substituted acyl (e.g.

phenylacetyl or phenoxyacetyl), camphorsulfonyl, alkyl-substituted sulfonyl (e.g.

methanesulfonyl), aliphatic or halo-aliphatic carboxylic acid-derived acyl groups (e.g. acetyl, valeryl, capryl, n-decanoyl, acryloyl, pivaloyl or chloroacetyl), esterified carboxyl (e.g. tert-butoxycarbonyl, ethoxycarbonyl, isobornyloxycarbonyl, phenyloxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl or A-methylsulfonylethoxycarbonyl), carbamoyl groups (e.g.

methylcarbamoyl, phenylcarbamoyl or naphthylcarbamoyl), and the corresponding thiocarbamoyl groups.

The group R2 is hydrogen or an ester residue. The ester residue may be one that is conventionally employed in the cephalosporin art. Thus R2 may for example be benzhydryl, tert-butyl, 2,2,2-trichloroethyl, p-nitrobenzyl, cyanomethyl, methylthiomethyl, methoxymethyl or pivaloyloxymethyl. In view of its ready availability, it is particularly desirable to employ the compound wherein R2 is hydrogen.

The compound of the general formula (I) may form salts with respect to its amino or carboxyl functions. Thus, it may form salts with inorganic acids such as hydrochloric acid, sulfuric acid or nitric acid; salts with organic acids such as ptoluenesulfonic acid or oxalic acid; salts with alkali metals or alkaline earth metals such as sodium, potassium, calcium or magnesium; salts with organic bases such as triethylamine, trimethylamine or triethanolamine.

The compound (II) or a salt thereof to be employed in the method of the present invention is prepared by carbamoylating a compound of the formula (III):

(wherein each of R'CO and R2 has the same meaning as defined above) or a salt thereof.

This reaction may be conducted by the known procedures, for example by the method described in Japanese Patent Application As Laid-open No. 16494/1972, No. 81887/1973, No. 67222/1973, No. 67290/1973, No. 32829/1973 and No.

52083/1975. Thus, to effect the carbamoylation, normally a compound of the general formula (III) is reacted with an isocyanate of the general formula (IV): R5NCO (IV) (wherein RS is a group substitutable by hydrogen) to produce a compound of the formula (V):

(wherein R'CO, R2 and R5 are as hereinbefore defined) and, then, R5 in this compound (V) is substituted by a hydrogen atom to yield a compound of the general formula (II). The choice of a compound of the general formula (V) and of reaction conditions may be made in accordance with the teachings of the aforementioned prior patent literature references. Among the isocyanates (R5NCO) mentioned in the above patent literature, compounds in which R5 is chlorosulfonyl, monohalogenoacetyl, dihalogenoacetyl or trihalogenoacetyl are preferred. As compound (IV), chlorosulfonyl isocyanate is particularly desirable.

Thus, this compound is reacted with a compound of the general formula (III) to yield the corresponding compound of formula (V). Then, by contacting it with water under acidic conditions. the compound (V) can be easily converted to a compound of the general formula (II).

It should be understood that, while a large majority of compounds of the general formula (III) are known compounds, new compounds may also be easily produced by procedures analogous to the known procedures.

The resulting compound of the general formula (II) is then silylated. This silylation is accomplished by reacting a compound of the general formula (IV) with a silylating agent.

The silylating agent may be a compound of the formula: P'P2P3Si . Hal, wherein each of pr, p2 and P3 is a hydrocarbon residue such as a lower alkyl of I to 4 carbon atoms (e.g. methyl, ethyl, n-propyl, i-propyl or n-butyl or an aryl group (e.g. phenyl or tolyl), and Hal is halogen, preferably chlorine or bromine, and one or two of pq, P2 and P3 may be halogen, preferably chlorine or bromine, and one of P1, p2 and P3 may be hydrogen. Furthermore, hexa-alkyl (C,-C,)cyclotrisilazane, octaalkyl (C,-C,)cyclotetrasilazane, trialkyl(C1-C4)silylacetamide, bis - tri alkyl(C1-C4)silylacetamide may be used as the silylating agent in the method of the present invention. The preferred silylating agents are alkyl(C1- C4)tri alogenosilane (e.g. trimethylsilylchloride), di-alkyl(C,-C,)dihalogenosilane (e.g. dimethyldichlorosilane), ' di - alkoxy(C,-C,)dihalogenosilane (e.g.

dimethoxydichlorosilane or diethoxydichlorosilane). This reaction is preferably conducted in the presence of a base (e.g. triethylamine, pyridine, picoline or N,Ndimethylaniline). While the reaction proceeds in the absence of a solvent, it is preferably conducted in an inert solvent such as dichloromethane, dichloroethane, chloroform, benzene, toluene or tetrahydrofuran. With respect to 1 mol of compound (II), the silylating agent is employed normally in excess, preferably in an amount of 1.2 to 2 mols relative to the theoretical amount. The base is desirable used in a proportion of 1 to 5 mols per compound (II). The reaction temperature is normally -20"C to 40"C and the reaction normally goes to completion within about one hour. After the reaction has been completed, the reaction mixture either as it is or after having been concentrated to a suitable concentration is subjected to the next reaction. By this silylation reaction, a silyl group is introduced into the carbamoyl group. Where the acyl group (R'CO) has a free carboxyl group and where R2 in COOR2 is hydrogen, silyl groups are also introduced into those carboxyl groups, producing silyl esters. It is disclosed in Japanese Patent Application Laid-open No. 40899/1970 that a silyl ester is an excellent protective group for the carboxy group in case of the removal of an acyl group.

The silylated compound thus obtained is subjected to a reaction for the cleavage of the amide linkage. The various techniques established in the art of cephalosporins for such amide-cleavage reactions may be utilized for this purpose.

For example, the procedures taught by Japanese Patent Publication No.

13862/1966 and Japanese Patent Application Laid-open No. 95292/1975 and No.

96591/1975 may be followed, for instance. The procedure according to the present invention comprises converting the silylated compound to an iminohalide and, then, the latter to an iminoether compound and, finally, subjecting the latter to solvolysis to obtain the compound of the general formula (I).

Thus, in the first place, the silylated compound is reacted with a halogenating agent such as phosphorus pentachloride to produce the iminohalide. With respect to each mol of silylated compound, from 1 to 4 mols of phosphorus pentachloride are employed. The reaction temperature is -500C to 45"C. The reaction is conducted in an inert solvent such as dichloromethane, chloroform.

tetrahydrofuran, benzene or toluene. Following this reaction for the production of the iminohalide, the reaction mixture is normally contacted with a C14 aliphatic alcohol to convert the iminohalide to the iminoether compound. The alcohol may.

for example, be methanol, ethanol or n-butanol. This reaction is normally carried out in an inert solvent such as dichloromethane, chloroform or tetrahydrofuran and at a temperature in the range of from -50"C to +450C. The reaction normally goes to completion within from 10 minutes to one hour. The resulting iminoether compound is subjected to solvolysis. The solvolysis is usually carried out by contacting the iminoether compound with an alcohol, e.g. the C1 aliphatic alcohol solvent or water, or the C14 aliphatic alcohol and water.

The amide linkage is cleaved by the solvolysis. The silyl group or groups are also removed by the action of the C14 aliphatic alcohol or water. Thus, the compound (I) or its salt is produced in excellent yield in accordance with the present invention. This solvolysis is normally conducted under acid conditions. The solvent is used in excess. The reaction temperature may be within the range of from -500C to 450 C, the reaction being completed in from 10 minutes to 1 hour. The acid condition may be attained by the presence of an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid in the reaction mixture. The pH value of the mixture is usually not higher than 1.

The amide-cleavage reaction may also be accomplished by reacting the iminohalide with hydrogen sulfide or thioacetamide to obtain the thioamide derivative, then activating this thioamide and subjecting this activated compound to solvolysis (see e.g. the specification of Japanese Patent Application Laid-open No. 96591/1975). The conditions of the reaction (e.g. the reaction temperature and the solvent between the iminohalide and hydrogen sulfide or thioacetamide may be similar to the conditions used for the aforesaid reaction for the production of the iminohalide and iminoether compounds. The thioamide compound may be activated, for example, by reacting it with trichloromethanesulfenyl chloride or sulfur monochloride. The solvolysis of the thus activated compound is effected by exactly the same procedure as the solvolysis of said iminoether compound and gives rise to the compound of formula (I).

Where R2 in the resulting compound of formula (I) is an ester residue, the compound in which R2 is hydrogen may be produced, if desired, by removing the ester residue in a routine manner, e.g. by hydrolysis, acid decomposition or reduction, in accordance with per se known procedures.

The solution containing the compound (I) may be directly subjected to the next reaction, or the compound (I) may be isolated beforehand. The isolation of the compound (I) may be conducted in a routine manner. For example, when the reaction mixture is allowed to cool in the neighbourhood of its isoelectric point, 7 ACC separates out from the mixture. This precipitate is recovered by filtration, washed with an organic solvent and water and dried. If desired, the compound may be further purified by a procedure which is well known per se.

A good embodiment of the present invention may be shown by the following reaction scheme:

HOCC)(CH2)3CcNH;MNc2 OCNH2 CII 0 silylating agent COOH Y1 OOCCH (CH2)3C0 R13 20Y2 COOT1 halogenating agent x1 y1 OOCCH (CH2)3 C=N S R3 OOCCH (CH2)3 an aliphatic Cocyl alcohol (ROH) OR v100CCH(CH2)3C=NH20Y2 o I COOY1 the aliphatic alcohol or land water (solvolysis) H2M 011 +\CH20CNH2 (7-ACO) COOH In the above scheme, R3 is a protected amino group; Y' is a silyl group; Y2 iS a silylated carbamoyl group; X' is halogen; and ROH is an aliphatic alcohol.

The end-products of the present invention are useful as the starting materials for the production of various cephem compounds having excellent antibacterial properties. In particular, 7-ACC and its salts are of value as the starting materials for the production of antibiotics having the formula (VI):

wherein n is a number in the range: 0=n < =l, and R4 is hydrogen or a lower alkyl, and pharmaceutically acceptable salts thereof. The compounds of the formula (Vl) may form pharmaceutically acceptable salts with respect to the carboxyl function or with respect to the group represented by the formula:

and the pharmaceutically acceptable salts may be salts with the acids or bases mentioned above regarding the compound (I).

The compound of formula (VI) in which R2 is hydrogen and R4 is hydrogen may be produced, for example, by the following reaction steps:

7- ACC or its salt } xOH2OOOH2OOX 2 OH2= OH2 XCH2COCH2COX - CH2= mCt H2 XCH2COCH2CONHomv So 0 2( NH2 CNH2 Nitrosating agent Nitrosating agent XOH2OOOCONH S N' I 011 OH OH2oONH2 COCH (E) H2NCSNH2 H2nN H nN1 OOONH S OOH COOH ( 1S (wherein n has the meaning defined hereinbefore; X is chlorine or bromine).

In the step of producing a compound (VII) from 7-ACC, the latter is acylated with 1 to 1.5 molar equivalents of a 4 - halogeno - 3 - oxobutyryl halogenide to give (VII). This acylation reaction is conducted in a solvent, such as dimethylformamide, dichloromethane, dimethylacetamide, dimethylsulfoxide.

chloroform or acetonitrile, or a mixture of such solvents, and in the presence of 1 to 3 molar equivalents of an organic base such as triethylamine, N,N-dimethylaniline or pyridine. This reaction is conducted at a temperature within the range of from -40 C to 400C, preferably under cooling at a temperature from -400C to OOC. The compound (VII) obtained is isolated as crystals by extraction and concentration.

The compound (VII) is then nitrosated to (VIII). Specifically, the compound (VII) is first dissolved in a solvent, e.g. acetic acid or aqueous acetic acid, and I to 2 molar equivalents of a nitrosating agent such as sodium nitrite are then added. The reaction is conducted at from -400C to +200 C. The product (VIII) is isolated as a powder by extraction and phase transfer operations.

Then (VIII) is reacted with 1 to 2 molar equivalents of thiourea to produce (IX). This reaction is conducted at 0 to 200C in a solvent, e.g. dimethylformamide, dimethylacetamide, dimethylsulfoxide or acetonitrile, or a mixture of solvents. The product (IX) is isolated and purified by such procedures as extraction, phase transfer, pH adjustment, crystallization and column chromatography.

Among compounds of the formula (VI), a compound (X), i.e. the compound (VI) wherein R2 is hydrogen and R4 is a lower alkyl group such as methyl, ethyl, npropyl or i-propyl:

(wherein Y is the C,, alkyl mentioned above; n has the meaning defined hereinbefore) may be produced by reacting a carboxylic acid of the formula (XI):

(wherein Y and n are as defined hereinbefore; and Z is hydrogen or a protective -group) or a reactive derivative thereof, with 7-A CC. In the above compound (XI), the protective group Z is exemplified by aromatic acyl groups such as benzoyl, benzoyl substituted by halogen, nitro or C14 alkyl (e.g. chlorobenzoyl, pnitrobenzoyl, p-tert-butylbenzoyl or toluoyl), naphthoyl, phenylacetyl, phenoxyacetyl, benzenesulfonyl, benzenesulfonyl substituted by C14 alkyl (e.g. p tertbutylbenzenesulfonyl or toluenesulfonyl), camphorsulfonyl, methanesulfonyl, aliphatic or haloaliphatic carboxylic acid-derived acyl groups (e.g. acetyl, valeryl, caprilyl, n-decanoyl, acryloyl, pivaloyl or halogenoacetyl (e.g. monochloroacetyl, monobromoacetyl, dichloroacetyl or trichloroacetyl), esterified carboxyl groups (e.g. ethoxycarbonyl, tert-butyloxycarbonyl, isobornyloxycarbonyl, phenyloxycarbonyl, trichloroethoxycarbonyl or benzyloxycarbonyl or carbamoyl groups (e.g. methylcarbamoyl, phenylcarbamoyl or naphthylcarbamoyl), and the corresponding thiocarbamoyl groups. The carboxylic acid thus protected or unprotected may be used, either as it is or as a reactive derivative thereof, as an acylating agent for acylating the 7-amino group of the compound (I). Thus, the free acid (Xl), a salt thereof with an alkali metal or alkaline earth metal (e.g. sodium, potassium or calcium) or with an organic amine (e.g. trimethylamine or pyridine) or a reactive derivative thereof, such as the acid halide (e.g. the acid chloride or acid bromide), acid anhydride, mixed acid anhydride, active amide or activated ester.

may be employed for the purpose of the above-mentioned acylation. As examples of the activated ester there may be mentioned the p-nitrophenyl ester, 2,4dinitrophenyl ester, pentachlorophenyl ester, N-hydroxysuccinimide ester and Nhydroxyphthalimide ester. The mixed acid anhydride is exemplified by mixed anhydrides with carbonic acid monoesters (e.g. monomethyl carbonate or monoisobutyl carbonate) and mixed anhydrides with C1 6 aliphatic carboxylic acids which may optionally be substituted by halogen (e.g. pivalic acid or trichloroacetic acid). Where the protected or unprotected carboxylic acid (Xl) is employed as it is or in the form of a salt, a suitable condensing agent is employed. As examples of the condensing agents there may be mentioned N,N' - di - substituted carbodiimides such as N,N' - dicyclohexylcarbodiimide; azolides such as N,N'-carbonylimidazole or N,N' - thionyldiimidazole; dehydrating agents such as N - ethoxycarbonyl - 2 ethoxy - 1,2 - dihydroquinoline, phosphorus oxychloride or alkoxyacetylene; and 2-halogenopyridinium salts (e.g. 2-chloropyridinium methyl iodide or 2fluoropyridinium methyl iodide). Where such condensing agents are employed. the reaction seems to proceed via a reactive derivative of the carboxylic acid (Xl). The reaction is generally conducted in a suitable solvent. As examples of the solvent there may be mentioned halogenated hydrocarbons such as chloroform or methylene chloride; ethers such as tetrahydrofuran or dioxane; dimethyl formamide, dimethylacetamide, acetone, water and mixtures thereof The proportion of the carboxylic acid (XI) or of the reactive derivative thereof is normally from 1 to a few molar equivalents per mol of the compound (I). This reaction is generally carried out at a temperature in the range of from -50 C to +40"C. After the acylation reaction, the protective group may be removed.

Removal of an amino-protecting group may be accomplished by procedures known per se, for example, the procedures described in Japanese Patent Application As Laid-open No. 52083/1975 or Pure and Applied Chemistry 7, 335 (1963). or by procedures analogous thereto. Where, for example, the protective group Z is a monohalogenoacetyl group (e.g. monochloroacetyl), removal of the monohalogenoacetyl from the amino group may be accomplished by reacting the acylated compound with its amino group thus protected with thiourea and a basic reagent. This reaction is normally conducted in a solvent in the neighbourhood of room temperature and, in many instances, goes to completion in from one to ten hours. The solvent may be any solvent that will not interfere with the reaction.

Thus, for example, ethers (e.g. ethyl ether, tetrahydrofuran or dioxane), C14 aliphatic-alcohols (e.g. methanol or ethanol) halogenated hydrocarbons (e.g.

chloroform or methylene dichloride), esters (e.g. ethyl acetate or butyl acetate), ketones (e.g. acetone or methyl ethyl ketone), water and mixtures thereof may be mentioned.

Reacting the protected compound (X) with thiourea and a basic reagent results in a selective and smooth progress of the reaction for the desired removal of the monohalogenoacetyl group and, hence, in the formation of the compound (X).

The basic reagent useful for this reaction is exemplified by the alkali metal or alkaline earth metal salts of C,~6 aliphatic carboxylic acids and inorganic or organic bases with pKa values of not less than 9.5, preferably pK values in the range of 9.8 to 12.0. As examples of the salts of C16 aliphatic carboxylic acids there may be mentioned, e.g., sodium acetate, potassium acetate, calcium acetate, barium acetate, sodium formate, sodium propionate and potassium hexanoate. As examples of said inorganic bases there may be mentioned the alkali metal salts of carbonic acid (e.g. sodium carbonate or potassium carbonate). As said organic bases, there may be mentioned amines which are mono-, di- or tri-substituted by C14 alkyl (e.g. trimethylamine, triethyalmine, ethylamine, methylamine.

diethylamine, dimethylamine, tributylamine, dibutylamine or butylamine) and 5 to 6-membered cyclic amines N-substituted by C12 alkyl (e.g. N-methylpyrrolidine.

N-ethylpyrrolidine, N-methylpiperazine or N-ethylpiperazine). While, as aforesaid, thiourea is employed in this reaction, it is also possible to employ N- or N.Nsubstituted thiourea (e.g. methylthiourea, N,N-diethylthiourea or N.Nhexamethylenethiourea) instead of thiourea.

The starting material (XI), e.g. 2 - (2 - aminothiazol - 4- yl)- 7- methoxyiminoacetic acid (syn-isomer) may be produced, for example, by the process described hereinafter in detail.

First a 4 - halogeno - 3 - oxo - 2 - hydroxyiminibutyric acid derivative of the general formula (XII):

[wherein X2 is halogen (e.g. chlorine or bromine); R4' is lower alkyl (e.g. methyl); R7 is lower alkyl (cm~3) (e.g. ethyl)] is reacted with thiourea to yield an 2 - (2 aminothiazol - 4 - yl) - 2 - methoxyiminoacetic acid derivative of the general formula (XIII):

(wherein R4 and R7 are as respectively defined above).

In this case, the compound (XIII) is obtained as a mixture of syn- and antiisomers. This reaction is normally conducted by permitting thiourea to act upon the compound (XII) in an organic solvent such as ethanol, methanol, tetrahydrofuran or the like at room temperature or at elevated temperature. The amount of thiourea may be from one to three mols per mol of the compound (XII).

From the resulting mixture of said syn- and anti-forms of the compound (XIII), the desired syn-isomer may be separated and recovered by a per se known procedure or by the procedure disclosed in Japanese Patent Application No.

108102/1976. The resulting compound (XI) wherein Z is hydrogen, if desired after the introduction of a protective group Z by a procedure known per se, may be converted to a reactive derivative thereof by a procedure which is also well known per se.

It should be mentioned that, in the above formulae, the moieties of

are each supposed to assume a tautomeric structure of 2-aminothiazole and 2iminothiazoline forms, thus:-

(2-aminothiazole form) (2-iminothiazoline form) The compounds (VI) and their pharmacologically acceptable salts, may be administered as injections just in the same way as the known cephalosporin and penicillin drugs. Thus, these compounds are novel compounds having excellent activity against a broad spectrum of microorganisms including Gram-negative bacteria such as Escherichia coli, Serratia marcescens, Proteus rettgeri, Enterobacter cloacae and Citrnbacterfreundll, and are p-lactamase-resistant. These compounds may be employed, for example, as disinfectants for removing the microorganisms from surgical instruments or as a therapeutic agent for the management of infectious diseases. When a compound (VI) or</R

Example 1 In dichloromethane (6 ml) is suspended benzhydryl 7 - phenylacetamido - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylate (427 mg). Following the addition of pyridine (300 mg), dimethyldichlorosilane (150 mg) is further added under ice-cooling. The mixture is stirred at room temperature for one hour, whereby the ester is completely dissolved. The solution is cooled to -200C and.

after phosphorus pentachloride (600 mg) is added, the mixture is stirred for 30 minutes. During this period of time, the temperature increases to -10"C. The mixture is cooled to -400C and methanol (4 ml) is added. It is then stirred for 15 minutes, after which water (6 ml) and tetrahydrofuran (4 ml) are added. The lavers are separated and the water layer is taken, while the organic layer is extracted with water. The water layers are combined, washed once with dichloromethane and neutralized with sodium hydrogen carbonate. It is then extracted with a solvent mixture of dichloromethane-tetrahydrofuran and the extract is washed with aqueous sodium chloride, dried, filtered and concentrated. To the residue is added petroleum ether, whereupon crystals separate out. By the above procedure is obtained benzhydryl 7 - amino - 3 - carbamoyloxymethyl - 3 - cephem - 4 carboxylate as crystals melting at 120 to 1220C.

IR (KBr, cm 1775, 1728 NMR (drDMSO): a 3.53 (2H, ABq, J=20Hz, 2-CH2), 4.66 (2H, ABq, J=13Hz, 3--CH,), 4.84 (it, d, J=SHz, 6-H), 5.03 (1H, d, J=5Hz, 7-H), 6.55 (2H, broad-s.

6.90 (1H, 5, -C11), 7.39 (ion, m).

Example 2 Dichloromethane (8.6 1) is cooled to -300C in a nitrogen gas stream and 7 - - 5 - p - t - butylbenzamido - 5 - carboxyvaleramido) - 3 - hydroxymethyl - cephem - 4 - carboxylic acid di-triethylamme salt (1.7 kg) is added. The mixture is stirred and anhydrous potassium carbonate (450 g) is then added and suspended in the mixture. At -25"C, the cooling bath is removed. Then, dichloromethane (11) containing chlorosulfonyl isocyanate (450 g) is added over a period of 5 minutes and the mixture is stirred at --100C for 40 minutes. The mixture is adjusted to pH 0.1 to 0.2 by the addition of 3N-hydrochloric acid and stirred at room temperature for 30 minutes. It is then adjusted to pH 2.7 with potassium carbonate and extracted with tetrahydrofuran (12 1). After the addition of triethylamine (580 g), the extract is concentrated, dissolved in dichloromethane (15 1), dried over anhydrous magnesium sulfate, filtered and concentrated to yield a syrupy substance. Upon the addition of ether (5 1), the syrup becomes a powder. The powder is recovered by filtration and dried. By the above proceudre is obtained 7 (D - 5 - p - t - butylbenzamido - 5 - carboxyvaleramido) - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid di-triethylamine salt as a crude powder (1.7 kg). While this product includes the lactone, it is fully useful for the next deacylation reaction. The above crude powder (3 g) is taken, purified by column chromatography on Amberlite (trade mark) XAD-2 and Sephadex (trade mark) LH-20, and lyophilized. The above procedure gives a high purity grade of 7 (D - 5 - p - t - butylbenzamido - 5 - carboxyvaleramido) - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid di-triethylamine salt (1.12 g).

IR (KBr, cm 1770, 1330 NMR (d6-DMSO): a 1.13 (1811, t,sJ=6HZ, Et3Nx2), 1.31 (9H s, t-Bu). 1.4--'.0 (4H, m -CH(CH2)2-CH-) 2.20 (2H, t, J=6Hz, -CH(C112)2CH2-) | 2.91 (12H, q, J=6Hz, Et3Nx2), 3.17 4 3.48 (2H, ABq, J=18Hz, 2-CH2), 4.24 (lH.

m, -CH(CH2)3-) | 4.66 & 4.87 (2H, ABq, J=13Hz, 3--CH,), 4.94 (1H, d, J-SHz, 6--H), 5.50 (1H, dd, J=5 & 8Hz, 7--H), 6A4 (2H, broad-s, CON112), 7.46 (2H, d, J=8Hz, Arom-H), 7.79 (2H, d, J=8Hz, Arom-H), 8.03 (1H, d, J=8Hz, -CONH-), 8.64 (1H, d, J=8Hz, -CONH-) Elemental analysis, for C38H62N6OgS . H2O Calcd.: C, 57.26; H,8.09; N, 10.54 Found: C, 57.17; H,8.41; N, 10.38 In nitrogen gas streams, 7 - (D - 5 - p- t - butylbenzamido - 5 carboxyvaleramido) - 3 - carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid di-triethylamine salt (1.7 kg) is dissolved in dichloromethane (7.3 1) and, then, N,N-dimethylaniline (2.6 1) and dimethyldichlorosilane (970 ml) are added. The mixture is stirred at 20 to 30 C for 40 minutes. Then, after cooling to -350C, phosphorus pentachloride (1.25 kg) is added in a single dose and the mixture is stirred at -200C for 15 minutes. Methanol (5.0 1) is added dropwise at -30 to -25"C, after which it is stirred at 200C for 20 minutes. Following the addition of water (4.0 1), the mixture is further stirred at 10 to 130C for 30 minutes. The mixture is adjusted to pH 3.5 with 20 /ó sodium carbonate and the resulting precipitate is recovered by filtration and washed with dichloromethane (5 1) and methanol (5 1).

By the above procedure there is obtained 7 - amino - 3 - carbamoyloxymethyl 3 - cephem - 4 - carboxylic acid as a crude powder (600 g). The powder is added to 4N-hydrochloric acid (2 1) and, after 15 minutes' stirring at room temperature, the insolubles are filtered off. To the filtrate is added ethyl acetate (300 ml) and the mixture is adjusted to pH 3.5 with 20% sodium carbonate. After the addition of methanol (2 1), the mixture is stirred under ice-cooling for 30 minutes. The resulting crystals are collected by filtration, washed 3 times with water (300 ml) and 3 times with acetone (400 ml). By this procedure there is obtained 7 - amino - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (175 g) of high purity.

UVAmax (pH 6.5, phosphate) 265 nm (E7885) IR (KBr, cm-1): 1800, 1710, 1333 NMR (d6-DMSO): a 3.34 & 3.57 (2H, ABq, J=18Hz, 2--CH,), 4.58 & 4.87 (2H, ABq, J=13Hz, 3-CH2), 4.76 (1H, d, J=5Hz, 6--H), 4.96 (1H, d, J=SHz, 7 H), 6.50 (2H, broad-s, -OCONH2) Elemental analysis, for C9H1,N305S.0.5H2O Calcd.: C. 38.29; 11, 4.29; N, 14.89 Found: C,38.84; H,4.25; N, 14.12 Example 3 7 - (D - 5 - phthalimido - 5 - carboxyvaleramido) - 3 - hydroxymethyl - 3 cephem - 4 - carboxylic acid (5.21 g) is dissolved in a mixture (1:1 volume/volume) of tetrahydrofuran and dichloromethane, and the solution is cooled to -350C.

Then, under stirring. a mixture of chlorosulfonyl isocyanate (2 ml) and dichloromethane (2 ml) is added rover a period of 10 minutes. During this period of time, the temperature is held at -35"C to 30C C. The temperature is then increased to 13"C and, following the addition of 3N-hydrochloric acid (10 ml), the mixture is stirred for 30 minutes. A saturated aqueous solution of sodium chloride (30 ml) is added and the organic layer is separated. To this organic layer is added a saturated aqueous solution of sodium chloride (10 ml) and water (10 ml) and, with stirring, the mixture is adjusted to pH 4.0 by the addition of aqueous sodium carbonate. The water layer is separated and washed with a mixture of tetrahydrofuran (20 ml) and dichloromethane (20 ml). The mixture (50 ml) of tetrahydrofuran and dichloromethane (1:1 volume/volume) is freshly added and, under stirring, hydrochloric acid is added to bring the pH to 2.5. The organic layer is separated, washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The concentration residue is dissolved in tetrahydrofuran (20 ml), and ethyl acetate (000 ml) is added. The mixture is concentrated to 60 ml and the precipitate is filtered off.

Ether (200 ml) is added to the filtrate and the precipitate is recovered by filtration, washed with ether and dried over phosphorus pentoxide. By the above procedure is obtained 7 - (D - 5 - phthalimido - 5 - carboxyvaleramido) - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (4.6 g).

IR (KBr, cm-1): 1789, 1330 NMR (d6-DMSO): a 1.26-2.36 (6H, m, -(C112)3-), 3.45 (2H, ABq, J=18Hz, 2-CH2), 4.74 (1H. t, J=7Hz, -CH 4.77 (2H, ABq, J=13Hz, 3-CH2), 5.06 (it, d, J=5Hz, 6-H), 5.62 (it, dd, J=5 & 8Hz, 7-H), 6.56 (2H, s, CONH2), 7.92 (4H, s, arom-H), 8.74 (1H, d, J=8Hz, --CONHH-).

7 - (D - phthalimido - 5 - carboxyvaleramido) - 3 - carbamoyloxymethyl 3- cephem - 4- carboxylic acid (4.6 g) is dissolved in a mixture of dichloromethane (30 ml), triethylamine (1.8 ml) and N,N-dimethylaniline (6.5 ml).

Then, dimethyldichlorosilane (3.0 ml) is added and the mixture is stirred at room temperature for one hour, after which it is cooled to -350C and phosphorus pentachloride (2.75 g) is added. The mixture is stirred at -30 to -250C for 15 minutes, after which time it is cooled to -40"C and methanol (15 ml) is gradually added. During this time, the temperature of the solution is maintained between -30 and -20"C.

Then, the mixture is stirred at -20 to -170C for 20 minutes, at the end of which time water (15 ml) is added. The mixture is adjusted to pH 3.7 by the addition of aqueous sodium carbonate and stirred under ice-cooling for one hour. The resulting precipitate is recovered by filtration, washed with dichloromethane, methanol and water in the order mentioned and dried over phosphorus pentoxide.

By the above procedure there is obtained 7 - amino - 3 - carbamoyloxymethyl 3 - cephem - 4 - carboxylic acid (1.70 g). In IR spectrum, this product agrees with the product obtained in Example 2.

Example 4 Deacetyl-cephalosporin C sodium monohydrate (7.0 g) is dissolved in water (19 ml), and this is followed by the addition of tetrahydrofuran (9 ml) and Ncarboethoxyphthalimide (6.8 g). Under stirring, an aqueous solution of potassium carbonate is added so as to maintain the pH value of the mixture at 9.1 to 9.3 for 30 minutes and at 9.7 to 9.8 for a succeeding hour. Thereafter, tetrahydrofuran (26 ml) and dichloromethane (32 ml) are added and, under ice-cooling and stirring, 3Nhydrochloric acid is added to bring the pH to 2.5. The organic layer is separated.

The water layer is extracted with a mixture of tetrahydrofuran (18 ml) and dichloromethane (18 ml) and the organic layers are combined, washed with aqueous sodium chloride and dried over anhydrous magnesium sulfate. The solvent is then distilled off, whereby a syrupy product is obtained as the residue. This residue is dissolved in tetrahydrofuran (25 ml) and dichloromethane (25 ml) is added. The mixture is cooled to -350C and, under stirring, a mixture of chlorosulfonyl isocyanate (2 ml) and dichloromethane (2 ml) is added over a period of 10 minutes. During this time, the temperature of the solution is maintained at -35 to -300C. The temperature is increased to 13"C over a period of 30 minutes and, after the addition of 3N-hydrochloric acid (10 ml), the mixture is stirred for 30 minutes. Following the addition of aqueous sodium chloride (30 ml), the organic layer is separated, washed with aqueous sodium chloride and dried over anhydrous magnesium sulfate. Following the addition of triethylamine (6.3 ml), the solvent is distilled off to recover a syrupy residue. This residue is dissolved in dichloromethane (50 ml), followed by the addition of N,N-dimethylaniline (13 ml) and, then, of dimethyldichlorosilane (6 ml). The mixture is stirred at room temperature for one hour. Then, the mixture is cooled to -400C and, under stirring, phosphorus pentachloride (5.5 g) is added. The mixture is held at -30 to -25"C for 15 minutes and is then cooled to -40"C. Methanol (30 ml) is gradually added at this temperature. During this time, the temperature of the solution is maintained at -30 to -17"C. The temperature is then maintained at -17"C for 20 minutes, at the end of which time, the mixture is adjusted to pH 3.7 with aqueous sodium carbonate and stirred under ice-cooling for one hour. The precipitate is recovered by filtration, washed with dichloromethane, methanol, water and acetone in the order mentioned and dried over phosphorus pentoxide. By the above procedure there is obtained 7 - amino - 3 - carbamoyloxymethyl - 3 cephem - 4 - carboxylic acid (2.32 g). In IR spectrum, this product is found to agree with the product obtained in Example 2.

Reference Example 1 Benzhydryl 7 - phenylacetamido - 3 - carbamoyloxymethyl - 3 - cephem 4 - carboxylate (139 mg) is suspended in dichloromethane (2 ml) and. after the addition of pyridine (100 mg), dimethyldichlorosilane (50 mg) is added under ice cooling. The mixture is stirred for 50 minutes to obtain a homogeneous solution.

An additional amount of pyridine (50 mg) is added, the mixture is cooled to20 C, and phosphorus pentachloride (200 mg) is added. Then, under ice-cooling, the mixture is stirred for 30 minutes, after which it is cooled to -10"C and water (2 ml) and tetrahydrofuran (2 ml) are added. The mixture is separated into phases and the organic layer is taken and assayed by thin layer chromatography. The chromatogram shows only a spot at the same Rf value as that of the starting compound. The above mixture is dried and concentrated, and the residue is treated with ether. The resulting crystals are recovered by filtration. The IR spectrum of this product is in complete agreement with that of benzhydryl 7phenylacetamido - 3 - carbamoyloxymethyl - 3 - cephem - 4 - carboxylate.

The same reaction as above is carried out without the use of dimethyldichlorosilane. The thin layer chromatography of this reaction product mixture revealed no spot of the starting compound, with the spot of no migration being evidenced (developer solvent; ethyl acetate: dichloromethane=8:2).

Reference Example 2 (1) Diketene (189 g) is dissolved in dichloromethane (945 ml) and, under cooling at 500C, chlorine (159 g) is introduced. Separately, 7 - amino - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (410 g) and triethylamine (334 g) are dissolved in a mixture dimethylformamide (1.5 1) and dichloromethane (1.5 1). After the solution has been cooled to -25"C, the above reaction mixture is added dropwise at a temperature not exceeding -18"C, at which temperature the mixture is stirred for 30 minutes. Then, phosphoric acid (1 kg), water (3.75 1), methyl ethyl ketone (8.5 1) and ethyl acetate (3 1) are added to the above reaction mixture and, under stirring, sodium chloride is added to saturation. The organic layer is taken and the water layer is extracted with methyl ethyl ketone (4.2 1) and ethyl acetate (1.5 1). The organic layers are combined, washed 3 times with a saturated aqueous solution of sodium chloride (1.5 1) and dehydrate over anhydrous magnesium sulfate. The solvent is then distilled off and ethyl acetate (500 ml) is added to the residue. The resulting crystals are collected by filtration and dried. By the above procedure there is obtained 7 - (3 - oxo - 4 - chlorobutyrylamino) - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (463 g).

IR (KBr, cm-1): 1773, 1745 (sh.), 1720, 1660, 1540, 1335 NMR (d6-DMSO): a 3.42 & 3.66 (2H, ABq, J=18Hz, 2-CH2), 3.60 (2H, s, --COCH,C, 4.56 (2H, s, CICH2), 4.64 & 4.94 (2H, ABq, J=13Hz, 3CH2), 5.f2 (1H, d, J=SHz, 6--H), 5.68 (1H, dd, J=5, & 8Hz, 7--H), 6.52 (2H, broad-s, CONH2), 9.02 (1H, d, J=8Hz, --CONHH-).

(2) In a mixture of acetic acid (2.8 1) and water (0.7 1) there is suspended 7 (3 - oxo - 4 - chlorobutyrylamino) - 3 - carbamoyloxymethyl - 3 - cephem - 4 carboxylic acid (463 g), and sodium nitrite (81.5 g) is added over a period of about 10 minutes, the temperature being maintained at 0 to 30C. After the addition has been completed, the mixture is stirred at the same temperature for 30 minutes, after which time phosphoric acid (500 ml), ethyl acetate (15 1) and water (4.5 1) are added. Then, sodium chloride is added to saturation. The organic layer is taken and the water layer is extracted with ethyl acetate (5 1). The organic layers are combined, washed twice with a saturated aqueous solution of sodium chloride (3.5 I) and dried over anhydrous magnesium sulfate. The solvent is distilled off and dichloromethane (500 ml) and petroleum ether (2 1) are added. The resulting precipitate is recovered by filtration and dried. By this procedure there is obtained 7 - (2 - hydroxyimino - 3 - oxo - 4 - chlorobutyrylamino) - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (syn-isomer) (433 g).

IR (KBr, cm-1): 1785, 1730 (sh), 1715, 1660, 1545, 1330 NMR (d6-DMSO): a 3.42 & 3.64 (2H, ABq, J=18Hz, 2H2), 4.62 & 4.92 (2H, ABq, J=13Hz, 3-CH2), 4.81 (2H, s, ClCH2-), 5.15 (1H, d, J=5Hz, 6-H), 5.78 (1H, dd, J=5 & 8Hz, ?--H), 6.52 (2H, broad-s, CONH2), 9.26 (1H, d, J=8Hz, -CONH-), 13.12 (1H, s, =N--OH).

(3) In dimethylacetamide (600 ml) is suspended 7 - (2 - hydroxyimino - 3 oxo - 4 - chlorobutrylamino)- 3 - carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (syn-isomer) (400 g) together with thiourea (76.1 g). The suspension is stirred dt room temperature for 6 hours, at the end of which time ether (3 1) is added. After stirring. the supernatant liquor is discarded.

Methanol (2 1) is added to the residual mixture. The resulting mixture is added dropwise to ethyl acetate (24 1). The resulting precipitate is recovered by filtration.

dissolved in methanol ( 1) and added dropwise to ethyl acetate (20 1). The precipitate is recovered by filtration and dried. This precipitate is dissolved in an aqueous solution of sodium hydrogen carbonate (160 g) and chromatographed on a column of Amberlite XAD-2. Development is carried out with water and the active fractions are pooled, concentrated and lyophilized. The lyophilizate is purified by column chromatography on Sephadex LH-20. The active fractions are concentrated and lyophilized. By the above procedure there is obtained sodium 7 [2 - (2 - imino - 4 - thiazolin - 4- yl)- 2- hydroxyiminoacetamidol - 3 carbamoyloxymethyl - 3 - cephem - 4 - carboxylate (syn-isomer) (118.5 g).

IR (KBr, cm~1): 1770, 1710, 1670, 1610, 1540, 1330 NMR (D2O): a 3.39 & 3.70 (2H, ABq, J=18Hz, 2-CM2), 4.70 & 4.92 (2H, ABq, J=13Hz, 3-CM2), 5.24(1H, d, J=SHz, 6--H), 5.86(1H, d, J=SHz, 7-H), 6.98 (1H, s, thiazoline 5--H).

UVAH2 nm (E): 225 (19700), 258 (15000).

Reference Example 3 (1) Ethyl 4 - chloro - 3 - oxo - 2 - hydroxyiminoacetate (121 g) and thiourea (47.6 g) are added to ethanol (600 ml) and the mixture is stirred at room temperature for 3 hours. The ethanol is distilled off under reduced pressure, and water (350 ml) is added to the residue. The water layer is washed with ether, neutralized (pH 7.5) with sodium hydrogen carbonate and extracted with a 1:1 (volume/volume) mixture of ethyl acetate and tetrahydrofuran. The organic layer is washed with water and dried. Thereafter, the solvent is distilled off to obtain a crystalline product (45 g).

This product is purified by chromatography on silica gel (developer system=ethyl acetate-n-hexane) and the anti-form of ethyl 2 - (2 - aminothiazol 4 - yl) - 2 - hydroxyiminoacetate is obtained from a leading portion of the eluate while thesyn-form of the same compound is obtained from a trailing portion of the eluate.

syn-Isomer: White crystals with a tingle of pale yellow; m.p. 185.5"C.

Elemental analysis, for C7HgN303S Calcd.: C, 39.06; H,4.21; No 19.52 Found: C, 39.28; H, 4.10; N, 19.63 NMR (d8-DMSO): a 6.80 (1H, s, thiazole 5-H), 7.12(2H, broad, s., NH2), 11.6 (1H, s, OH).

(2) Sodium carbonate (10.6 g) is dissolved in water (150 ml) and a solution of ethyl 2 - (2 - aminothiazol - 4 - yl) - 2 - hydroxyiminoacetate (syn-isomer) (10.7 g) in a mixture of tetrahydrofuran (150 ml) and methanol (50 ml) is added. Under icecooling, dimethyl sulfate (12.6 g) is added dropwise over a period of 5 minutes.

After the dropwise addition has been completed, the ice bath is removed and the mixture is stirred at room temperature. In this stage, a white crystalline substance begins to separate out. After 3 hours, a major part of the organic solvent is distilled off and the residue is cooled with ice. The precipitate is recovered by filtration, rinsed with water and dried.

By the above procedure there is obtained ethyl 2 - (2 - aminothiazol - 4 yl) - 2 - methoxyiminoacetate (syn-isomer) as white crystals melting at 163 to 1640C.

Elemental analysis, for C8H11N303S Calcd.: C,41.91: H, 4.84; N, 18.33 Found: C,41.57; H, 4.76; N, 18.07 NMR (CDCl3) a: 4.02 (3H, s, OCH3), 5.80 (2H, broad, s., NH2), 6.74 (1H, s, thiazole-5H).

(3) In N,N-dimethylformamide (10 ml) is dissolved ethyl 2 - (2 - aminothiazol - 4 - yl) - 2 - methoxyiminoacetate (syn-isomer, m.p. 163 to 164 C) (2.15 g) and, under ice-cooling, chloroacetyl chloride (1.27 g) is added dropwise.

The mixture is stirred under ice-cooling for 30 minutes and, then, at room temperature for 30 minutes, at the end of which time water (50 ml) is added. The mixture is extracted twice with ethyl acetate (100 ml each). The extracts are combined, washed with 5% aqueous sodium hydrogen carbonate and a saturated aqueous solution of sodium chloride in the order mentioned and dried. The solvent is distilled off, whereupon ethyl 2 - (2 - chloroacetamidothiazol - 4 - yl) - 2 methoxyiminoacetate (syn-isomer) is obtained as crystals melting at 111 to 112"C.

Elemental analysis, for C1oHl2N3o4scl Calcd.: C, 39.29; H,3.96; N, 13.74 Found: C,39.15; H,3.91; N, 13.69 NMR (CDCl3): 4.00 (3H, s, NOCH3), 4.24 (2H, s, CICH2CO), 7.15 (1H, s, thiazole 5-H).

(4) Ethyl 2 - (2 - chloroacetamidothiazol - 4 - yl) - 2 - methoxyiminoacetate (syn-isomer) (9.62 g) is dissolved in a solution containing water (85 ml), ethanol (452 ml) and potassium hydroxide (9 g). The mixture is stirred at room temperature for 2 hours. The ethanol is distilled off under reduced pressure and water (85 ml) is added to the residue. The mixture is washed with ethyl acetate (100 ml) and the water layer is adjusted to pH 2 with 10% hydrochloric acid and extracted twice with 200 ml portions of ethyl acetate. The extracts are combined, washed with a saturated aqueous solution of sodium chloride and dried. The solvent is then distilled off, whereupon 2 - (2 - chloroacetamidothiazol - 4- yl)- 2methoxyiminoacetic acid (syn-isomer) is obtained as crystals melting at 170 to 171"C.

Elemental analysis, C8H8N804SCI Calcd.: C,34.60; H,2.90; N, 15.13 Found: C, 34.97; H,3.03; N, 14.74 NMR (d6-DMSO): 63.95 (3H, s, NOCH3), 4.40 (2H, s, CICH2CO), 7.57 (it, s, thiazole 5-H).

(5) In dry tetrahydrofuran (60 ml) there is dissolved 2 - (2 - chloroacetamidothiazol - 4 - yl) - 2 - methoxyiminoacetic acid (syn-isomer) (1.5 g) and, under stirring, triethylamine (0.55 g) is added. The mixture is cooled to -100C and isobutyl chloroformate (0.74 g) is added dropwise. The mixture is stirred at that temperature for 2 hours. To the resulting mixed acid anhydride solution is added a solution (ice-cooled) of triethylamine (0.55 g) and 7- amino - 3carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (1.5 g) in 50% aqueous tetrahydrofuran (60 ml). The mixture is stirred under ice-cooling for one hour and, then, at room temperature, for 2 hours. After a major part of the tetrahydrofuran is distilled off under reduced pressure, water (600my) and, then, ethyl acetate (120 ml) are added. The mixture is adjusted to pH about 2 with IN-hydrochloric acid and separated into two phases. The water layer is extracted 3 times with ethyl acetate (150 ml each). The ethyl acetate layers are combined, washed with water, dried and concentrated to recover 1.75 g of 7 - [2 - (2 - chloroacetamidothiazol 4 - yl) - 2 - methoxyiminoacetamido] - 3 - carbamoyloxymethyl - 3 - cephem -.

4 - carboxylic acid.

The entire amount of this product is dissolved in tetrahydrofuran (45 ml), and after the addition of thiourea (0.6 g) and sodium acetate trihydrate (1 g), the mixture is stirred at room temperature for 4 hours. The precipitate is recovered by filtration, dissolved in water (30 ml) and adjusted to pH about 7.0 with sodium hydrogen carbonate. It is then purified by passage through a column of Amberlite XAD-2. By the above procedure there is obtained sodium 7 - [2 - (2 aminothiazol - 4 - yl) - 2 - methoxyiminoacetamido] - 3 - carbamoyloxymethyl 3 - cephem - 4 - carboxylate (syn-isomer) as white powders. 100 mg.

NMR spectrum (D2O): a 3.48 (2H, q, 2-CH2), 3.92 (3H, s, OCH3), 4.16 (2H

Claims (12)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   Elemental analysis, for C1oHl2N3o4scl Calcd.: C, 39.29; H,3.96; N, 13.74 Found: C,39.15; H,3.91; N, 13.69 NMR (CDCl3): ô 4.00 (3H, s, NOCH3), 4.24 (2H, s, CICH2CO), 7.15 (1H, s, thiazole 5-H).

   (4) Ethyl 2 - (2 - chloroacetamidothiazol - 4 - yl) - 2 - methoxyiminoacetate (syn-isomer) (9.62 g) is dissolved in a solution containing water (85 ml), ethanol (452 ml) and potassium hydroxide (9 g). The mixture is stirred at room temperature for 2 hours. The ethanol is distilled off under reduced pressure and water (85 ml) is added to the residue. The mixture is washed with ethyl acetate (100 ml) and the water layer is adjusted to pH 2 with 10% hydrochloric acid and extracted twice with 200 ml portions of ethyl acetate. The extracts are combined, washed with a saturated aqueous solution of sodium chloride and dried. The solvent is then distilled off, whereupon 2 - (2 - chloroacetamidothiazol - 4- yl)- 2methoxyiminoacetic acid (syn-isomer) is obtained as crystals melting at 170 to 171"C.

   Elemental analysis, C8H8N804SCI Calcd.: C,34.60; H,2.90; N, 15.13 Found: C, 34.97; H,3.03; N, 14.74 NMR (d6-DMSO): 63.95 (3H, s, NOCH3), 4.40 (2H, s, CICH2CO), 7.57 (it, s, thiazole 5-H).

   (5) In dry tetrahydrofuran (60 ml) there is dissolved 2 - (2 - chloroacetamidothiazol - 4 - yl) - 2 - methoxyiminoacetic acid (syn-isomer) (1.5 g) and, under stirring, triethylamine (0.55 g) is added. The mixture is cooled to -100C and isobutyl chloroformate (0.74 g) is added dropwise. The mixture is stirred at that temperature for 2 hours. To the resulting mixed acid anhydride solution is added a solution (ice-cooled) of triethylamine (0.55 g) and 7- amino - 3carbamoyloxymethyl - 3 - cephem - 4 - carboxylic acid (1.5 g) in 50% aqueous tetrahydrofuran (60 ml). The mixture is stirred under ice-cooling for one hour and, then, at room temperature, for 2 hours. After a major part of the tetrahydrofuran is distilled off under reduced pressure, water (600my) and, then, ethyl acetate (120 ml) are added. The mixture is adjusted to pH about 2 with IN-hydrochloric acid and separated into two phases. The water layer is extracted 3 times with ethyl acetate (150 ml each). The ethyl acetate layers are combined, washed with water, dried and concentrated to recover 1.75 g of 7 - [2 - (2 - chloroacetamidothiazol 4 - yl) - 2 - methoxyiminoacetamido] - 3 - carbamoyloxymethyl - 3 - cephem -.

   4 - carboxylic acid.

   The entire amount of this product is dissolved in tetrahydrofuran (45 ml), and after the addition of thiourea (0.6 g) and sodium acetate trihydrate (1 g), the mixture is stirred at room temperature for 4 hours. The precipitate is recovered by filtration, dissolved in water (30 ml) and adjusted to pH about 7.0 with sodium hydrogen carbonate. It is then purified by passage through a column of Amberlite XAD-2. By the above procedure there is obtained sodium 7 - [2 - (2 aminothiazol - 4 - yl) - 2 - methoxyiminoacetamido] - 3 - carbamoyloxymethyl 3 - cephem - 4 - carboxylate (syn-isomer) as white powders. 100 mg.

   NMR spectrum (D2O): a 3.48 (2H, q, 2-CH2), 3.92 (3H, s, OCH3), 4.16 (2H, q, 3--CH,), 5.27 (1H, d, 6--H), 5.70 (1H, d, 7--H), 6.95 (1H, s, thiazole 5-H).

   WHAT WE CLAIM IS: 1. A method for producing a cephem compound of the formula (I):

   wherein R2 is hydrogen or an ester residue. or a salt thereof, which comprises silylating a compound of the formula (II):

   wherein R1CO is an acyl group and R2 has the same meaning as defined above, or a salt thereof, with a silylating agent to produce a compound silylated at the carbamoyl group of the 3 position; reacting the silylated compound with a halogenating agent to produce the corresponding iminohalide; reacting the iminohalide with a C14 aliphatic alcohol to produce the corresponding iminoether compound, and subjecting the iminoether compound to solvolysis.
2. 2. A method as claimed in claim 1, wherein R2 is hydrogen, and the acyl group is a group of the formula:

   wherein R3 is a protected amino group.
3. 3. A method as claimed in claim 2, wherein the acyl group is 5 - p - t butylbenzamido - 5 - carboxyvaleryl.
4. 4. A method as claimed in claim 2, wherein the acyl group is D - 5 - p - r butylbenzamido - 5 - carboxyvaleryl.
5. 5. A method as claimed in claim 2, wherein the acyl group is 5-phthalimido-5carboxyvaleryl.
6. 6. A method as claimed in claim 2, wherein the acyl group is D - 5 phthalimido - 5 - carboxyvaleryl.
7. 7. A method as claimed in any one of claims 1 to 6, wherein the silylating agent is dimethyldichlorosilane.
8. 8. A method as claimed in any one of claims I to 6, wherein the C14 aliphatic alcohol is methanol.
9. 9. A method as claimed in any one of claims 1 to 6 wherein the halogenating agent is phosphorus pentachloride.
10. 10. A method as claimed in claim 1, wherein R1CO- is D - 5 - p - t butylbenzamino - 5 - carboxyvaleryl or D - 5 - phthalimido - 5 - carboxyvaleryl, the silylating agent is dimethyldichlorosilane, the halogenating agent is phosphorus pentachloride and the C14 aliphatic alcohol is methanol.
11. 11. A method as claimed in claim 1 substantially as herein described with reference to any of the specific examples.
12. 12. Cephem compounds of the formula (I) as defined in claim I when produced by a method as claimed in any of claims 1 to 11.