Cephalosporins, process for their preparation, intermediates and pharmaceutical compositions

Abstract: Cephalosporin antibiotics having a 3-position substituent of the formula: are described; wherein R¹ is hydrogen or certain substituted alkyl groups, Z is CH or N, R² and R³ are hydroxy or in vivo hydrolysable esters thereof, (R¹²) n represents various optional substituents and X = Y is an olefin, oxime, azo or related group. Processes for their preparation and use are described.

Description: The present invention relates to cephalosporins and in particular to such compounds comprising an amide group. This invention further relates to processes for their preparation, to intermediates in their preparation, to their use as therapeutic agents and to pharmaceutical compositions containing them. The compounds of this invention are antibiotics and can be used in the treatment of any disease that is conventionally treated with antibiotics for example in the treatment of bacterial infection in mammals including humans. The compounds of this invention also have non-therapeutic uses as they can be used in conventional manner in industry for example they can be used as disinfectants and food preservatives. The compounds of this invention, however, are primarily of therapeutic interest as they show a desirable profile of activity in their antibacterial effect. Investigation into new cephalosporin derivatives has been intense over the past 25 years with many thousands of patents and scientific papers having been published. A particular problem associated with the commercially available cephalosporins is the lack of potency against strains of Pseudomonas. The present invention provides cephalosporin derivatives having novel 3-position substituents, which derivatives possess good antibacterial activity and in particular against strains of Pseudomonas. A further problem associated with many commercially available cephalosporins is the lack of stability to β-lactamase enzyme producing organisms and the consequent loss of antibacterial activity. The compounds of the present invention exhibit good stability to β-lactamase enzymes and thus are particularly useful in treating organisms that are β-lactamase producers. The cephalosporin derivatives referred to herein are generally named in accordance with the 'cephem' nomenclature and numbering system proposed in J.A.C.S. 1962, 84 ,3400. Accordingly the present invention provides a cephalosporin compound having a 3-position substituent of the formula (I): wherein: R¹ is hydrogen, C₁₋₆ alkyl optionally substituted by any of halo, hydroxy, C₁₋₆ alkoxy, carboxy, amino, cyano, C₁₋₆ alkanoylamino, phenyl or heteroaryl, or R¹ is C₂₋₆ alkenyl; R² is hydroxy or an in vivo hydrolysable ester thereof; R³ is hydroxy or an in vivo hydrolysable ester thereof; Z is CH or N; X is a group CR⁴, wherein R⁴ is hydrogen, optionally substituted C₁₋₆alkyl, aryl, arylC₁₋₆ alkyl, heteroaryl or heteroaryl C₁₋₆alkyl; Y is a group NOR⁵, NNR⁵¹R⁶, NR⁷ (when -X=Y is ortho to a hydroxy group) or CR⁸R⁹, wherein R⁵ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁵¹ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆alkenyl, optionally substituted C₃₋₇cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆alkanoyl, arylC₁₋₆alkanoyl, heteroarylC₁₋₆alkanoyl, optionally substituted C₂₋₆alkenoyl, optionally substituted C₃₋₇cycloalkylcarbonyl, arylcarbonyl, heteroarylcarbonyl, carbamoyl, C₁₋₆alkylcarbamoyl, arylcarbamoyl or arylC₁₋₆alkylcarbamoyl; R⁶ is hydrogen, C₁₋₆ alkyl or arylC₁₋₆alkyl; R⁷ is optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁸ and R⁹ are independently halogen, hydrogen, optionally substituted C₁₋₆ alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆ alkenyl, C₃₋₇ cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆ alkanoyl, optionally substituted C₁₋₆ alkoxycarbonyl, carboxy, arylcarbonyl, heteroarylcarbonyl or aryl C₁₋₆ alkoxycarbonyl; or X = Y is a group -N=N-R¹⁰ or, when Z is N, X = Y is also a group -N=CR¹⁰R¹¹ wherein R¹⁰ is optionally substituted aryl and R¹¹ is hydrogen or C₁₋₆alkyl; R¹² is C₁₋₆alkyl, halo, hydroxy, hydroxy C₁₋₆alkyl, cyano, trifluoromethyl, nitro, amino, C₁₋₆alkylamino, di-C₁₋₆alkylamino, C₁₋₆alkanoyl, C₁₋₆alkoxy, C₁₋₆alkylthio, C₁₋₆alkanoyloxy, carbamoyl, C₁₋₆alkylcarbamoyl, di-C₁₋₆alkylcarbamoyl, carboxy, carboxy C₁₋₆alkyl, C₁₋₆alkoxycarbonylC₁₋₆alkyl, sulpho, sulphoC₁₋₆alkyl, C₁₋₆ alkanesulphonamido, C₁₋₆alkoxycarbonyl, C₁₋₆alkanoylamino, thioureido or amidino, and n is zero to 2. When used herein the term "heteroaryl" means a 5- or 6-membered ring containing 1 to 3 ring atoms selected from nitrogen, oxygen and sulphur and may be optionally substituted, for example by the substituents described hereinabove as values for R¹². Examples of heteroaryl include furanyl, pyridinyl, thiazolyl and isothiazolyl. Examples of aryl include phenyl and naphthyl, either of which may be optionally substituted, for example by the substituents described hereinabove as values for R¹². In one aspect R¹ may be C₁₋₆ alkyl substituted by heteroaryl for example R¹ may be pyridinylmethyl or furanylmethyl. Particular meanings for R¹ are hydrogen, C₁₋₆ alkyl for example methyl, ethyl or propyl, hydroxy C₁₋₆alkyl for example 2-hydroxyethyl, halo C₁₋₆alkyl for example 2-chloroethyl or 2-fluoroethyl, C₁₋₆alkoxyC₁₋₆alkyl for example 2-methoxyethyl, 2-ethoxyethyl or methoxymethyl, carboxy C₁₋₆alkyl for example carboxymethyl, phenyl C₁₋₆alkyl for example benzyl or phenethyl, or C₂₋₆alkenyl for example allyl. Preferably R¹ is hydrogen, methyl or ethyl. Most preferably R¹ is hydrogen. R² is hydroxy or an in vivo hydrolysable ester thereof. In vivo hydrolysable esters are those pharmaceutically acceptable esters that hydrolyse in the human or animal body to produce the parent hydroxy compound. Such esters can be identified by administering, e.g. intravenously to a test animal, the compound under test and subsequently examining the test animal's body fluids. Suitable in vivo hydrolysable esters include C₁₋₆ alkanoyloxy for example acetoxy, propionyloxy, pivaloyloxy, C₁₋₄alkoxycarbonyloxy for example ethoxycarbonyloxy, phenylacetoxy and phthalidyl. R³ is hydroxy or an in vivo hydrolysable ester thereof. Conveniently both R² and R³ have the same value and are both hydroxy or are both in vivo hydrolysable esters, for example they are both acetoxy or pivaloyloxy. In one aspect X is a group CR⁴. In a particular aspect R⁴ is C₁₋₆ alkyl (for example methyl, ethyl, n-propyl or n-butyl) optionally substituted. Suitable substituents include hydroxy, halo for example bromo, chloro or fluoro, C₁₋₆ alkoxy for example methoxy or ethoxy, amino, C₁₋₆ alkylamino for example methylamino or ethylamino, and di-C₁₋₆ alkylamino for example dimethylamino or diethylamino. In another aspect R⁴ is aryl for example phenyl or phenyl substituted by C₁₋₆ alkyl, or R⁴ is heteroaryl for example furanyl, or R⁴ is aryl C₁₋₆ alkyl for example benzyl or phenethyl, or R⁴ is heteroarylC₁₋₆alkyl for example pyridinylmethyl or furanylmethyl. Particular meanings for R⁴ are hydrogen, methyl, ethyl, n-propyl, n-butyl, phenyl, benzyl and furanyl. Most favourably R⁴ is hydrogen. In one aspect Y is a group NNR⁵¹R⁶. In another aspect Y is a group NR⁷ in which case the substituent -X=Y is located in a position ortho to a hydroxy group on the benzene or pyridine ring of the formula (I). Generally such a hydroxy group will be one of R² and R³. In a preferred aspect Y is a group NOR⁵ so forming an oxime. R⁵ is hydrogen, optionally substituted C₁₋₆ alkyl (for example methyl, ethyl, n-propyl, isopropyl or n-butyl), arylC₁₋₆alkyl (for example benzyl or phenethyl), heteroarylC₁₋₆alkyl (for example furanylmethyl), optionally substituted C₂₋₆ alkenyl (for example allyl), optionally substituted C₃₋₇ cycloalkyl (for example cyclobutyl, cyclopentyl, or cyclohexyl), aryl (for example phenyl or naphthyl) or heteroaryl (for example pyridinyl, furanyl or imidazolyl). Suitable optional substituents for alkyl, cycloalkyl and alkenyl include hydroxy, C₁₋₆ alkoxy for example methoxy and ethoxy, halo for example bromo, chloro or fluoro, carboxy, C₁₋₄alkylcarbamoyl for example methylcarbamoyl, di-C₁₋₄alkylcarbamoyl for example dimethylcarbamoyl, C₁₋₆alkylthio for example methylthio, amino, C₁₋₆alkylamino for example methylamino and ethylamino, di-C₁₋₆alkylamino for example dimethylamino and diethylamino, cyano, C₁₋₆alkanesulphonamido for example methanesulphonamido, C₁₋₆alkoxycarbonyl for example methoxycarbonyl and ethoxycarbonyl or C₁₋₆alkanoyl. Particular meanings for OR⁵ include hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy, t-butoxy, cyclopropoxy, cyclobutoxy, cyclopentoxy, allyloxy, 2-chloroethoxy, 2-fluoroethoxy, 2-bromoethoxy, 2-hydroxyethoxy, 3-hydroxypropoxy, 2-methoxyethoxy, 2-ethoxyethoxy, 2-methylthioethoxy, 2-aminoethoxy, 3-aminopropoxy, 2-methylaminoethoxy, 2-dimethylaminoethoxy, cyanomethoxy, 2-cyanoethoxy, carboxymethoxy, 2-carboxyethoxy, 1-carboxyethoxy, 1-carboxycyclobutoxy, 1-carboxycyclopentoxy, 2-carboxyprop-2-oxy, methoxycarbonylmethoxy, ethoxycarbonylmethoxy, acetoxy and benzyloxy. R⁵¹ is hydrogen, optionally substituted C₁₋₆ alkyl (for example methyl, ethyl, n-propyl, isopropyl or n-butyl), arylC₁₋₆alkyl (for example benzyl or phenethyl), heteroarylC₁₋₆alkyl (for example furanylmethyl), optionally substituted C₂₋₆ alkenyl (for example allyl), optionally substituted C₃₋₇ cycloalkyl (for example cyclobutyl, cyclopentyl, or cyclohexyl), aryl (for example phenyl or naphthyl), heteroaryl (for example pyridinyl, furanyl or imidazolyl), C₁₋₆alkanoyl (for example formyl, acetyl or propionyl), arylC₁₋₆ alkanoyl (for example phenylacetyl), heteroarylC₁₋₆alkanoyl (for example furanylacetyl), optionally substituted C₂₋₆alkenoyl (for example propenecarbonyl), optionally substituted C₃₋₇ cycloalkylcarbonyl (for example cyclopentylcarbonyl), arylcarbonyl (for example benzoyl), heteroarylcarbonyl (for example furancarbonyl), carbamoyl, C₁₋₆alkylcarbamoyl (for example methylcarbamoyl), arylcarbamoyl (for example phenylcarbamoyl) and arylC₁₋₆ alkylcarbamoyl (for example benzylcarbamoyl). Suitable optional substituents for alkyl, cycloalkyl and alkenyl include hydroxy, C₁₋₆ alkoxy for example methoxy and ethoxy, halo for example bromo, chloro or fluoro, carboxy, C₁₋₄alkylcarbamoyl for example methylcarbamoyl, di-C₁₋₄alkylcarbamoyl for example dimethylcarbamoyl, C₁₋₆alkylthio for example methylthio, amino, C₁₋₆alkylamino for example methylamino and ethylamino, di-C₁₋₆alkylamino for example dimethylamino and diethylamino, cyano, C₁₋₆alkanesulphonamido for example methanesulphonamido, C₁₋₆alkoxycarbonyl for example methoxycarbonyl and ethoxycarbonyl or C₁₋₆alkanoyl. R⁶ is hydrogen, C₁₋₆ alkyl for example methyl, ethyl or n-propyl, or arylC₁₋₆alkyl for example benzyl or phenethyl. Particular meanings for -NR⁵¹R⁶ include anilino, optionally substituted anilino, benzoylamino, phenylacetamido, ureido, methylureido and N¹-benzylureido (-N(CONH₂)CH₂Ph). R⁷ is optionally substituted C₁₋₆ alkyl (for example methyl, ethyl, n-propyl, isopropyl or n-butyl), arylC₁₋₆alkyl (for example benzyl or phenethyl), heteroarylC₁₋₆alkyl (for example furanylmethyl), optionally substituted C₂₋₆ alkenyl (for example allyl), C₃₋₇ cycloalkyl (for example cyclobutyl, cyclopentyl, or cyclohexyl), aryl (for example phenyl or naphthyl) or heteroaryl (for example pyridinyl, furanyl or imidazolyl). Suitable optional substituents for alkyl and alkenyl include hydroxy, C₁₋₆ alkoxy for example methoxy and ethoxy, halo for example bromo, chloro or fluoro, carboxy, C₁₋₄alkylcarbamoyl for example methylcarbamoyl, di-C₁₋₄alkylcarbamoyl for example dimethylcarbamoyl, C₁₋₆alkylthio for example methylthio, amino, C₁₋₆ alkylamino for example methylamino and ethylamino, di-C₁₋₆alkylamino for example dimethylamino and diethylamino, cyano, C₁₋₆ alkanesulphonamido for example methanesulphonamido, C₁₋₆ alkoxycarbonyl for example methoxycarbonyl and ethoxycarbonyl or C₁₋₆ alkanoyl. In another preferred aspect Y is a group CR⁸R⁹. R⁸ and R⁹ are independently halogen (for example chloro, bromo or fluoro), hydrogen, optionally substituted C₁₋₆ alkyl (for example methyl, ethyl, n-propyl, isopropyl or n-butyl), arylC₁₋₆alkyl (for example benzyl or phenethyl), heteroarylC₁₋₆alkyl (for example furanylmethyl), optionally substituted C₂₋₆ alkenyl (for example allyl), C₃₋₇ cycloalkyl (for example cyclobutyl, cyclopentyl, or cyclohexyl), aryl (for example phenyl or naphthyl), heteroaryl (for example pyridinyl, furanyl or imidazolyl), optionally substituted C₁₋₆ alkoxycarbonyl (for example methoxycarbonyl or ethoxycarbonyl), carboxy, arylcarbonyl (for example benzoyl), heteroarylcarbonyl (for example furanoyl or pyridinecarbonyl), optionally substituted C₁₋₆ alkanoyl (for example acetyl or propionyl) or aryl C₁₋₆ alkoxycarbonyl (for example benzoxycarbonyl). Suitable optional substituents for alkyl, alkenyl, alkoxycarbonyl, alkanoyl and any aryl or heteroaryl group include hydroxy, C₁₋₆ alkoxy for example methoxy and ethoxy, halo for example bromo, chloro or fluoro, carboxy, C₁₋₄alkylcarbamoyl for example methylcarbamoyl, di-C₁₋₄alkylcarbamoyl for example dimethylcarbamoyl, C₁₋₆alkylthio for example methylthio, amino, C₁₋₆alkylamino for example methylamino and ethylamino, di-C₁₋₆alkylamino for example dimethylamino and diethylamino, cyano, C₁₋₆alkanesulphonamido for example methanesulphonamido, C₁₋₆alkoxycarbonyl for example methoxycarbonyl and ethoxycarbonyl or C₁₋₆alkanoyl. Particular meanings for R⁸ and R⁹ include hydrogen, methyl, ethyl, phenyl, acetyl, methoxycarbonyl and pyridinyl. In another aspect the group -X=Y is -N=NR¹⁰ or, when Z is N, X = Y may also be -N=CR¹⁰R¹¹. R¹⁰ is aryl (for example phenyl or naphthyl) and optional substituents include hydroxy, C₁₋₆ alkoxy (for example methoxy or ethoxy), cyano, nitro, halo (for example chloro, bromo or fluoro), C₁₋₆alkyl (for example methyl) and C₁₋₆alkylthio (for example methylthio). R¹¹ is hydrogen or C₁₋₆ alkyl (for example methyl or ethyl). Preferably -X=Y is a group -N=NR¹⁰ for example phenylazo or 2,4,6-trimethylphenylazo. Particular values for R¹² are C₁₋₆alkyl for example methyl or ethyl, halo for example chloro, fluoro or bromo, hydroxy, hydroxyC₁₋₆alkyl for example hydroxyethyl, cyano, amino, C₁₋₆alkylamino for example methylamino or ethylamino, di-C₁₋₆alkyl amino for example dimethylamino or diethylamino, C₁₋₆alkoxy for example methoxy or ethoxy, carboxyC₁₋₆alkyl for example carboxymethyl, C₁₋₆alkanoylamino for example acetamido, trifluoromethyl, carboxy, carbamoyl, C₁₋₆alkylcarbamoyl for example methylcarbamoyl, di-C₁₋₆alkylcarbamoyl for example dimethylcarbamoyl, C₁₋₆alkanoyl for example acetyl, C₁₋₆alkylthio for example methylthio, C₁₋₆ alkanoyloxy for example acetoxy, C₁₋₆ alkoxycarbonyl for example methoxycarbonyl or ethoxycarbonyl and C₁₋₆ alkoxycarbonylC₁₋₆alkyl for example methoxycarbonylmethyl. Of these, favoured substituents are bromo, chloro, fluoro, nitro, cyano and hydroxy. Preferably n is zero or one. It will be realised, of course, that the present invention covers all isomeric and tautomeric forms of the aforementioned compounds. In particular most groups -X=Y may exist in cis- or trans form or in E- or Z- configuration, as appropriate. The present invention also covers mixtures of such isomers. A favoured class of cephalosporin compounds of the present invention has a 3-position substituent of the formula (II): wherein Z is as hereinbefore defined and R¹³ is hydrogen, C₁₋₆alkyl, benzyl, carboxyC₁₋₆alkyl or allyl. In particular R¹³ is hydrogen, methyl, ethyl, carboxymethyl, allyl or benzyl. In particular Z is -CH=. A further favoured class of cephalosporin compounds of the present invention is that of the formula (IIa): wherein Z is as hereinbefore defined and R⁰ is phenyl or 2,4,6-trimethylphenol. In particular Z is -N=. As stated hereinbefore the present invention relates to cephalosporins having a novel 3-position substituent. A particular class of cephalosporins within the present invention is that of the formula (III): and salts and esters thereof wherein R¹-R³, Z, n, X, Y and R¹² are as hereinbefore defined; X¹ is sulphur, oxygen, methylene or sulphinyl; R¹⁵ is hydrogen, methoxy or formamido; and R¹⁴ and R¹⁶ are groups known for such positions in the cephalosporin art. Preferably X¹ is sulphur. Preferably R¹⁵ is hydrogen. R¹⁴ is for example 2-aminothiazol-4-yl or 2-aminooxazol-4-yl each optionally substituted in the 5-position by fluorine, chlorine or bromine, or R¹⁴ is 5-aminoisothiazol-3-yl, 5-amino-1,2,4-thiadiazol-3-yl, 3-aminopyrazol-5-yl, 3-aminopyrazol-4-yl, 2-aminopyrimidin-5-yl, 2-aminopyrid-6-yl, 4-aminopyrimidin-2-yl, 2-amino-1,3,4-thiadiazol-5-yl or 5-amino-1-methyl-1,2,4-triazol-3-yl; R¹⁶ is for example of the formula =N.O.R¹⁷ (having the syn configuration about the double bond) wherein R¹⁷ is hydrogen, (1-6C)alkyl, (3-8C)cycloalkyl, (1-3C)alkyl(3-6C)cycloalkyl, (3-6C)cycloalkyl(1-3C)alkyl, (3-6C)alkenyl, optionally substituted by carboxy, (5-8C)cycloalkenyl, (3-6C)alkynyl, (2-5C)alkylcarbamoyl, phenylcarbamoyl, benzylcarbamoyl, (1- 4C)alkylcarbamoyl(1-4C)alkyl, di(1-4C)alkylcarbamoyl(1-4C)alkyl, (1-4C)haloalkylcarbamoyl(1-4C)alkyl, (1-3C)haloalkyl, (2-6C)hydroxyalkyl, (1-4C)alkoxy(2-4C)alkyl, (1-4C)alkylthio(2-4C)alkyl, (1-4C)alkanesulphinyl(1-4C)alkyl, (1-4C)alkanesulphonyl(1-4C)alkyl, (2-6C)aminoalkyl, (1-4C)alkylamino(1-6C)alkyl, (2-8C)dialkylamino(2-6C)alkyl, (1-5C)cyanoalkyl, 3-amino-3-carboxypropyl, 2-(amidinothio)ethyl, 2-(N-aminoamidinothio)ethyl, tetrahydropyran-2-yl, thietan-3-yl, 2-oxopyrrolidinyl, or 2-oxotetrahydrofuranyl, or R¹⁷ is of the formula IV:- -(CH₂) q -C(COOH)=CR¹⁸R¹⁹ (IV) wherein q is one or two and R¹⁸ and R¹⁹ are independently hydrogen or C₁₋₄alkyl; or R¹⁷ is of the formula V:- -CR²⁰R²¹-(CH₂) r -COR²² (V) wherein r is 0-3, R²⁰ is hydrogen, (1-3C)alkyl or methylthio, R²¹ is hydrogen, (1-3C)alkyl, (3-7C)cycloalkyl, cyano, carboxy, (2-5C)carboxyalkyl or methanesulphonylamino, or R²⁰ and R²¹ are joined to form, together with the carbon to which they are attached, a (3-7C)carbocyclic ring, and R²² is hydroxy, amino, (1-4C)alkoxy, (1-4C) alkylamino or of the formula NHOR²³ in which R²³ is hydrogen or (1-4C)alkyl; or R¹⁶ may be of the formula =CH.R²⁴ wherein R²⁴ is hydrogen, halogen, (1-6C)alkyl, (3-7C)cycloalkyl, (2-6C)alkenyl, (3-7C)cycloalkenyl, phenyl or benzyl. Particular meanings for R¹⁷ are hydrogen, methyl, ethyl, isopropyl, t-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopropyl, methylcyclobutyl, methylcyclopentyl, methylcyclohexyl, cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, allyl, cyclopentenyl, cyclohexenyl, propargyl, methylcarbamoyl, ethylcarbamoyl, phenylcarbamoyl, benzylcarbamoyl, 2-chloroethyl, 2-fluoroethyl, 2-bromoethyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-methoxyethyl, 2-ethoxyethyl, 2-methylthioethyl, 2-methanesulphinylethyl, 2-methanesulphonylethyl, 2-aminoethyl, 3-aminopropyl, 2-methylaminoethyl, 2-dimethylaminoethyl, cyanomethyl, 2-cyanoethyl, azidomethyl, 2-azidoethyl, ureidomethyl, 3-amino-3-carboxypropyl, 2-(amidino)ethyl, 2-(N-aminoamidino)-ethyl, tetrahydropyran-2-yl, thietan-3-yl, 2-oxopyrrolidinyl and 2-oxotetrahydrofuran-3-yl, or, when R¹⁷ is of the formula IV in which q is 1 or 2, a particular meaning for R¹⁷ is when R¹⁸ and R¹⁹ are hydrogen or methyl, or, when R¹⁷ is of the formula V a particular meaning for R¹⁷ is when r=0 and R²⁰ is hydrogen, methyl or methylthio, R²¹ is hydrogen, methyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyano, carboxy, carboxymethyl, 2-carboxyethyl or methanesulphonylamino, or when R²⁰ and R²¹ are joined to form, together with the carbon to which they are attached, a cyclopropane, cyclobutane, cyclopentane, cyclohexane or cycloheptane ring and R²² is hydroxy, amino, methoxy, ethoxy, methylamino, ethylamino, or of the formula NHOR²³ in which R²³ is hydrogen, methyl or ethyl. Preferably R¹⁷ is C₁₋₆alkyl for example methyl or ethyl, 1-carboxycyclobutyl, 1-carboxycyclopentyl, or 2-carboxyprop-2-yl. In particular R¹⁷ is 2-carboxyprop-2-yl. Particular meanings for R²⁴ are hydrogen, methyl, ethyl or chlorine. A particularly preferred class of cephalosporins of the present invention is that wherein R¹⁴ is 2-aminothiazol-4-yl, R¹⁶ is a group =NOR¹⁷ wherein R¹⁷ is C₁₋₆alkyl, 1-carboxycyclobutyl, 1-carboxycyclopentyl or 2-carboxyprop-2-yl, R¹⁵ is hydrogen, X¹ is sulphur and the 3-position substituent is of the formula (II) or (IIa). As stated hereinbefore the compounds of this invention are primarily intended for use in therapy. Therefore in a preferred aspect the present invention provides a cephalosporin compound having a 3-position substituent of the formula I or a pharmaceutically acceptable salt or ester thereof. Suitable salts include acid addition salts such as hydrochloride, hydrobromide, citrate, maleate and salts formed with phosphoric and sulphuric acid. In another aspect suitable salts are base salts such as an alkali metal salt for example sodium or potassium, an alkaline earth metal salt for example calcium or magnesium, an organic amine salt for example triethylamine, morpholine, N-methylpiperidine, N-ethylpiperidine, procaine, dibenzylamine, or N,N-dibenzylethylamine. In order to use a compound of the present invention or a pharmaceutically acceptable salt or ester thereof for the therapeutic treatment of mammals including humans, in particular in treating infection, it is normally formulated in accordance with standard pharmaceutical practice as a pharmaceutical composition. Therefore in another aspect the present invention provides a pharmaceutical composition which comprises a cephalosporin compound having a 3-position substituent of the formula I or a pharmaceutically acceptable salt or ester thereof and a pharmaceutically acceptable carrier. The pharmaceutical compositions of this invention may be administered in standard manner for the disease condition that it is desired to treat, for example by oral, rectal or parenteral administration. For these purposes it may be formulated by means known to the art into the form of, for example, tablets, capsules, aqueous or oily solutions or suspensions, emulsions, dispersible powders, suppositories and sterile injectable aqueous or oily solutions or suspensions. In addition to the pharmaceutically acceptable cephalosporin derivative of the present invention the pharmaceutical composition of the invention may also contain, or be co-administered with, one or more known drugs selected from other clinically useful antibacterial agents (for example other beta-lactams or aminoglycosides), inhibitors of beta-lactamase (for example clavulanic acid), renal tubular blocking agents (e.g. probenicid) and inhibitors of metabolising enzymes (for example inhibitors of peptidases, for example Z-2-acylamino-3-substituted propenoates). A preferred pharmaceutical composition of the invention is one suitable for intravenous, subcutaneous or intramuscular injection, for example a sterile injectable containing between 1 and 50% w/w of the cephalosporin derivative, or one suitable for oral administration in unit dosage form, for example a tablet or capsule which contains between 100 mg. and 1 g. of the cephalosporin derivative. The pharmaceutical compositions of the invention will normally be administered to man in order to combat infections caused by bacteria, in the same general manner as that employed for cephalothin, cefoxitin, cephradine, ceftazidime and other known clinically used cephalosporin derivatives, due allowance being made in terms of dose levels for the potency of the cephalosporin derivative of the present invention relative to the known clinically used cephalosporins. Thus each patient will receive a daily intravenous, subcutaneous or intramuscular dose of 0.05 to 30 g., and preferably 0.1 to 10 g., of the cephalosporin derivative, the composition being administered 1 to 4 times per day, preferably 1 or 2 times a day. The intravenous, subcutaneous and intramuscular dose may be given by means of a bolus injection. Alternatively the intravenous dose may be given by continuous infusion over a period of time. Alternatively each patient will receive a daily oral dose which is approximately equivalent to the daily parenteral dose. Thus a preferred daily oral dose is 0.5 to 10 g. of the cephalosporin derivative, the composition being administered 1 to 4 times per day. In a further aspect the present invention provides a process for preparing a cephalosporin compound having a 3-position substituent of the formula (I), which process comprises: (a) reacting a cephalosporin compound having a 3-position substituent of the formula: -CH₂NHR¹ wherein R¹ is as hereinbefore defined with a compound of the formula (VI): wherein R², R³, X, Y, R¹² and n are as hereinbefore defined and L is a leaving group; or b) for compounds of the formula (III), reacting a compound of the formula (VII) with a compound of the formula (VIII) or a reactive derivative thereof: wherein R¹-R³, R¹², R¹⁴-R¹⁶, n, X, X¹ and Y are as hereinbefore defined; or c) for compounds of the formula (III) wherein R¹⁶ is a group = NOR¹⁷, reacting a compound of the formula (IX): wherein R¹-R³, R¹², R¹⁴, R¹⁵, X¹, X, Y and n are as hereinbefore defined, with a compound of the formula: R¹⁷ONH₂ wherein R¹⁷ is as hereinbefore defined; or d) for compounds of the formula (III) wherein R¹⁶ is a group =NOR¹⁷ and R¹⁷ is other than hydrogen, reacting a compound of the formula (III) as hereinbefore defined wherein R¹⁶ is a group =NOH with compound of the formula (X): L¹ - R²⁵ (X) wherein L¹ is a leaving group and R²⁵ is a group R¹⁷ other than hydrogen; or e) for compounds of the formula (III) forming a group R¹⁴ by cyclising an appropriate precursor thereof: wherein any functional groups are optionally protected: and thereafter, if necessary: i) removing any protecting group, ii) for preparing in vivo hydrolysable esters, esterifying corresponding hydroxy groups, iii) converting compounds wherein X¹ is S to compounds wherein X¹ is sulphinyl and vice versa, iv) forming a pharmaceutically acceptable salt. In the reaction between a cephalosporin compound having a 3-position substituent of the formula -CH₂NHR¹, and a compound of the formula (VI), conveniently L is a leaving group such as halo for example chloro, bromo or iodo. Most suitably the reaction is performed under conditions conventional for the reaction of acid halides with amines for example in the presence of an organic amine such as triethylamine. Suitably the reaction is performed at an ambient or lower temperature in a substantially inert solvent such as dimethylformamide and/or dichloromethane. In an alternative aspect the leaving group L is part of an activated ester formed with the acid precursor of the compound of the formula VI, i.e. a compound wherein L is -OH provides an activated ester, e.g. dicyclohexylcarbodi-imide provides an activated ester of the formula VI wherein L is -OC(NHC₆H₁₁)=NC₆H₁₁, which group is displaced by the cephalosporin having a 3-position substituent of the formula: -CH₂NHR¹. Formation and reaction of the active ester is performed in conventional manner in the presence of reaction promotors such as hydroxybenzotriazole and triethylamine, for example in a substantially inert organic solvent such as dimethylformamide at a non-extreme temperature such as 10 o C-50 o C. The cephalosporin starting-materials for this reaction are known from the art, or are made by methods analogous to those of the art. See for example EP-A-127992 and EP-A-164944. The compounds of the formula VI are either known in the art or are made by methods analogous thereto. For example compounds wherein L is chloro are conveniently prepared from the corresponding acids. The acids are known or are prepared by methods known to those skilled in the art, for example as in the hereinafter described Examples. In particular the group -CR⁴=CR⁸R⁹ may be formed by the reaction of an appropriate aldehyde or ketone with a Wittig reagent, optionally using the Horner modification. Alternatively groups -CR⁴=CR⁸R⁹, in particular where one or both of R⁸ and R⁹ is electron-withdrawing, can be formed by a standard aldol condensation or reaction of an appropriate aldehyde or ketone with an activated methylene group (e.g. Knoevenagel condensation). A further method of forming certain groups -CH=CR⁸R⁹ is to react a aldehyde in the Perkin condensation. The above methods of forming carbon-carbon double bonds are illustrative only and the skilled man will be aware of alternative methods. The groups -CR⁴=NOR⁵, -CR⁴=NNR⁵¹R⁶ and -CR⁴=NR⁷ can, for example, be formed in standard manner by reacting an appropriate aldehyde or ketone with a hydroxylamine derivative, an appropriate hydrazine, acyl hydrazine, semicarbazine (NH₂NR′CONHR″) or an appropriate amine. The groups -N=NR¹⁰ and -N=CR¹⁰R¹¹ can, for example, be formed in standard manner by diazotisation or by reaction of an amine with an appropriate aldehyde or ketone. The reaction between compounds of the formulae VII and VIII is performed under conditions conventional in the cephalosporin art, for example under standard acylation conditions wherein for example the acid is activated as an acid bromide, acid chloride, anhydride or activated ester, or the reaction is performed in the presence of a coupling reagent such as dicyclohexylcarbodi-imide. The compounds of the formula VII can be prepared in a manner analogous to that described for the compounds having the 3-substituent of the formula I, with the 7-amino group being optionally protected. The reaction between compounds of the formula IX and R¹⁷ONH₂ is performed under conditions standard in the general chemical and/or cephalosporin art. The compounds of the formula IX can be prepared in a manner analogous to that described for the compounds having the 3-substituent of the formula I. The reaction between the compound of the formula III wherein R¹⁶ is a group =NOH and a compound of the formula X is performed under conditions standard in the general chemical and/or cephalosporin art. A group R¹⁴ may be formed by cyclizing an appropriate precursor. For example compounds of the formulae XI and XII: NH₂CSNH₂ (XII) wherein R¹-R³, R¹², R¹⁵, R¹⁶, X¹, X, Y and n are as hereinbefore defined and L² is a leaving group, may be reacted to form a 2-aminothiazol-4-yl group. A nitrogen atom of the thiourea may be optionally protected during this cyclization. The compounds of the formula XI can be prepared in a manner analogous to that described for the compounds having a 3-substituent of the formula I. The compounds of the formulae VIII, X and R¹⁷ONH₂ are known from, or can be made by the methods of, the general chemical and/or cephalosporin art. The compounds of the formulae VII, IX and XI are novel and as such form a further aspect of the present invention. In the process of this invention any functional group can be optionally protected, if appropriate. Such protecting groups may in general be chosen from any of the groups described in the literature or known to the skilled chemist as appropriate for the protection of the group in question, and may be introduced by conventional methods. Protecting groups may be removed by any convenient method as described in the literature or known to the skilled chemist as appropriate for the removal of the protecting group in question, such methods being chosen so as to effect removal of the protecting group with minimum disturbance of groups elsewhere in the molecule. Specific examples of protecting groups are given below for the sake of convenience, in which "lower" signifies that the group to which it is applied, preferably as 1-4 carbon atoms. It will be understood that these examples are not exhaustive. Where specific examples of methods for the removal of protecting groups are given below these are similarly not exhaustive. The use of protecting groups and methods of deprotection not specifically mentioned is of course within the scope of the invention. A carboxyl protecting group may be the residue of an ester-forming aliphatic or araliphatic alcohol or of an ester-forming phenol, silanol or stannanol (the said alcohol, phenol, silanol or stannanol preferably containing 1-20 carbon atoms). Examples of carboxyl protecting groups include straight or branched chain (1-12C)alkyl groups (eg isopropyl, t -butyl); halo lower alkyl groups (eg 2-iodoethyl, 2,2,2-trichloroethyl); lower alkoxy lower alkyl groups (eg methoxymethyl, ethoxymethyl, isobutoxymethyl); lower aliphatic acyloxy lower alkyl groups, (eg acetoxymethyl, propionyloxymethyl, butyryloxymethyl, pivaloyloxymethyl); lower alkoxycarbonyloxy lower alkyl groups (eg 1-methoxy-carbonyloxyethyl, 1-ethoxycarbonyloxyethyl); aryl lower alkyl groups (eg p-methoxybenzyl, o -nitrobenzyl, p -nitrobenzyl, benzhydryl and phthalidyl); tri(lower alkyl)silyl groups (eg trimethylsilyl and t-butyldimethylsilyl); tri(lower alkyl)silyl lower alkyl groups (eg trimethylsilylethyl); and (2-6C)alkenyl groups (eg allyl and vinylethyl). Methods particularly appropriate for the removal of carboxyl protecting groups include for example acid-, base-, metal- or enzymically-catalysed hydrolysis. Examples of hydroxyl protecting groups include lower alkanoyl groups (eg acetyl); lower alkoxycarbonyl groups (eg t -butoxycarbonyl); halo lower alkoxycarbonyl groups (eg 2-iodoethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl); aryl lower alkoxycarbonyl groups (eg benzoyloxycarbonyl, p -methoxybenzyloxycarbonyl, o -nitrobenzyloxycarbonyl, p -nitrobenzyloxycarbonyl); tri lower alkylsilyl (eg trimethylsilyl, t -butyldimethylsilyl) and aryl lower alkyl (eg benzyl) groups. In addition two hydroxy groups substituted on adjacent carbon atoms, for example in the catechol moiety, may be protected in the form of a cyclic acetal such as the methylenedioxy moiety. Examples of amino protecting groups include formyl, aralkyl groups (eg benzyl and substituted benzyl, eg p -methoxybenzyl, nitrobenzyl and 2,4-dimethoxybenzyl, and triphenylmethyl); di- p -anisylmethyl and furylmethyl groups; acyl (eg alkoxycarbonyl and aralkoxycarbonyl eg t -butoxycarbonyl and benzyloxycarbonyl); trialkylsilyl (eg trimethylsilyl and t -butyldimethylsilyl); alkylidene (eg methylidene); benzylidene and substituted benzylidene groups; and the phthalimido group. The following biological test methods, data and Examples serve to illustrate this invention. Antibacterial Activity The pharmaceutically acceptable cephalosporin compounds of the present invention are useful antibacterial agents having a broad spectrum of activity in vitro against standard laboratory microorganisms, both Gram-negative and Gram-positive, which are used to screen for activity against pathogenic bacteria. The antibacterial spectrum and potency of a particular compound may be determined in a standard test system. In particular the cephalosporins of the present invention show good stability to β-lactamase enzymes and have particularly high activity in vitro against strains of Pseudomonas aeruginosa and other Gram-negative aerobic bacteria. The antibacterial properties of the compounds of the invention may also be demonstrated in vivo in conventional mouse protection tests. Cephalosporin derivatives have generally been found to be relatively non-toxic to warm-blooded animals, and this generalisation holds true for the compounds of the present invention. Compounds representative of the present invention were administered to mice at doses in excess of those required to afford protection against bacterial infections, and no overt toxic symptoms or side effects attributable to the administered compounds were noted. The following results were obtained for representative compounds on a standard in vitro test system using Isosensitest agar medium. The antibacterial activity is described in terms of the minimum inhibitory concentration (MlC) determined by the agar-dilution technique with an inoculum size of 10⁴ CFU/spot. Examples 1 - 12 To a suspension of the appropriate 3-aminomethyl cephalosporin (1mM) in dimethylformamide (10ml), at 0 o C, was added triethylamine (3mM) followed by the appropriate activated ester (1.1mM) in dimethylformamide (5ml). The reaction mixture was stirred at 0 o C for 30 minutes and subsequently at room temperature for 4 hours. The mixture was concentrated to about 2.5ml under reduced pressure and the residue diluted with ice-cold water (50ml) to give a precipitate which was collected by filtration and purified on Diaion HP2OSS resin using acetonitrile/0.2% aqueous trifluoroacetic acid in gradient elution (increasing acetonitrile). Evaporation and freeze-drying of the appropriate fractions gave the desired product. The following general procedure was used for preparing the activated ester used in the above reaction: To the appropriate benzoic acid (1.5mM) and N-hydroxy succinimide (1.65mM) in dimethylformamide (4ml) and dichloromethane (4ml) was added dicyclohexylcarbodi-imide (1.65mM) over about 3 minutes. The reaction mixture was stirred for 3-4 hours at 20 o C, filtered to remove dicyclohexyl urea and the filtrate concentrated to about 5ml volume. This solution was used directly without further purification. The activated esters for preparing the compounds of Examples 1 to 12 were obtained from the corresponding benzoic acids as described. Data for these benzoic acids is given below: Examples 13-15 To a stirred solution of 2-phenylazo-3,4-dihydroxypyridin-6-carboxylic acid (0.6mM) and N-hydroxysuccinimide (0.6mM) in dimethylsulphoxide (2ml) was added dicyclohexylcarbodi-imide (0.6mM) and the mixture was stirred for 1 hour at room temperature. This mixture was subsequently added to a stirred, partial solution of the appropriate 3-aminomethyl cephalosporin (0.5mM) and triethylamine (1.0mM) in dimethylsulphoxide (2ml) and the mixture was stirred for a further 2 hours. The reaction mixture was acidified with glacial acetic acid, diluted with water (approx. 20ml), sodium acetate (1g) was added and the mixture filtered and the filtrate was purified by medium pressure chromatography on HP2OSS resin (gradient eluting with aqueous acetonitrile). The product was collected, acetonitrile removed by evaporation and the residue was freeze-dried, triturated with ether and dried under vacuum. Using the appropriate precursors the compounds of Examples 14 and 15 were obtained in analogous manner. The cephalosporin starting-materials are known from EP-A-127992 and EP-A-164944. The pyridine carboxylic acid starting-materials were prepared as follows: To a stirred solution of aniline (11mM) in 2N HCl (11ml) at 0 o C, was slowly added a solution of sodium nitrite (11mM) in water (1ml). The solution was stirred for 10 minutes and was then slowly added to a stirred solution of comenamic acid (10mM) in 2.5N NaOH (20ml) at 0 o C. Water (20ml) was added during the addition to assist stirring. The mixture was stirred for 2 hours. The solution was extracted with ethyl acetate and the organic phase was discarded. The aqueous phase was acidified to pH2, precipitating the product as a semi-solid mass. The suspension was stirred with ethyl acetate and the two-phase mixture was filtered. The product was washed with water, followed by a little ethyl acetate and then dried under vacuum; NMR (DMSO-d₆) 7.50(s,1H); 7.65(m,3H); 8.05(m,2H): MS. FAB (M-H) 258. In analogous manner 2,4,6-trimethylaniline gave 2-(2,4,6-trimethylphenylazo)-3,4-dihydroxypyridin-6-carboxylic acid; NMR (DMSO-d₆) 2.50(s,9H); 7.02(s,2H); 7.41(s,1H); MS FAB (M-H) 300.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, FR, GB, IT, LI, LU, NL, SE A cephalosporin compound having a 3-position substituent of the formula (I): wherein: R¹ is hydrogen, C₁₋₆ alkyl optionally substituted by any of halo, hydroxy, C₁₋₆ alkoxy, carboxy, amino, cyano, C₁₋₆ alkanoylamino, phenyl or heteroaryl, or R¹ is C₂₋₆ alkenyl; R² is hydroxy or an in vivo hydrolysable ester thereof; R³ is hydroxy or an in vivo hydrolysable ester thereof; Z is CH or N; X is a group CR⁴, wherein R⁴ is hydrogen, optionally substituted C₁₋₆alkyl, aryl, arylC₁₋₆ alkyl, heteroaryl or heteroaryl C₁₋₆alkyl; Y is a group NOR⁵, NNR⁵¹R⁶, NR⁷ (when -X=Y is ortho to a hydroxy group) or CR⁸R⁹, wherein R⁵ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁵¹ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆alkenyl, optionally substituted C₃₋₇cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆alkanoyl, arylC₁₋₆alkanoyl, heteroarylC₁₋₆alkanoyl, optionally substituted C₂₋₆alkenoyl, optionally substituted C₃₋₇cycloalkylcarbonyl, arylcarbonyl, heteroarylcarbonyl, carbamoyl, C₁₋₆alkylcarbamoyl, arylcarbamoyl or arylC₁₋₆alkylcarbamoyl; R⁶ is hydrogen, C₁₋₆ alkyl or arylC₁₋₆alkyl; R⁷ is optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁸ and R⁹ are independently halogen, hydrogen, optionally substituted C₁₋₆ alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆ alkenyl, C₃₋₇ cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆ alkanoyl, optionally substituted C₁₋₆ alkoxycarbonyl, carboxy, arylcarbonyl, heteroarylcarbonyl or aryl C₁₋₆ alkoxycarbonyl; or X = Y is a group -N=N-R¹⁰ or, when Z is N, X = Y is also a group -N=CR¹⁰R¹¹ wherein R¹⁰ is optionally substituted aryl and R¹¹ is hydrogen or C₁₋₆alkyl; R¹² is C₁₋₆alkyl, halo, hydroxy, hydroxy C₁₋₆alkyl, cyano, trifluoromethyl, nitro, amino, C₁₋₆alkylamino, di-C₁₋₆alkylamino, C₁₋₆alkanoyl, C₁₋₆alkoxy, C₁₋₆alkylthio, C₁₋₆alkanoyloxy, carbamoyl, C₁₋₆alkylcarbamoyl, di-C₁₋₆alkylcarbamoyl, carboxy, carboxy C₁₋₆alkyl, C₁₋₆alkoxycarbonylC₁₋₆alkyl, sulpho, sulphoC₁₋₆alkyl, C₁₋₆ alkanesulphonamido, C₁₋₆alkoxycarbonyl, C₁₋₆alkanoylamino, thioureido or amidino, and n is zero to 2. A compound according to claim 1 wherein R² and R³ are both hydroxy. A compound according to claim 1 wherein the cephalosporin compound has a 3-position substituent of the formula (II): wherein Z is -CH= or -N= and R¹³ is hydrogen, C₁₋₆alkyl, benzyl, carboxyC₁₋₆alkyl or allyl. A compound according to claim 1 wherein the cephalosporin compound has a 3-position substituent of the formula (IIa): wherein Z is -CH= or -N= and R⁰ is phenyl or 2,4,6-trimethylphenol. A compound according to any one of claims 1 to 4 of the formula (III): or a salt or ester thereof wherein R¹, R², R³, n,Z,X,Y and R¹² are as defined in any preceding claim; X¹ is sulphur, oxygen, methylene or sulphinyl; R¹⁵ is hydrogen, methoxy or formamido; R¹⁴ is 2-aminothiazol-4-yl or 2-aminooxazol-4-yl each optionally substituted in the 5-position by fluorine, chlorine or bromine, or R¹⁴ is 5-aminoisothiazol-3-yl, 5-amino-1,2,4-thiadiazol-3-yl, 3-aminopyrazol-5-yl, 3-aminopyrazol-4-yl, 2-aminopyrimidin-5-yl, 2-aminopyrid-6-yl, 4-aminopyrimidin-2-yl, 2-amino-1,3,4-thiadiazol-5-yl or 5-amino-1-methyl-1,2,4-triazol-3-yl; R¹⁶ is of the formula =N.O.R¹⁷ (having the syn configuration about the double bond) wherein R¹⁷ is hydrogen, (1-6C)alkyl, (3-8C)cycloalkyl, (1-3C)alkyl(3-6C)cycloalkyl, (3-6C)cycloalkyl(1-3C)alkyl, (3-6C)alkenyl, optionally substituted by carboxy, (5-8C)cycloalkenyl, (3-6C)alkynyl, (2-5C)alkylcarbamoyl, phenylcarbamoyl, benzylcarbamoyl, (1- 4C)alkylcarbamoyl(1-4C)alkyl, di(1-4C)alkylcarbamoyl(1-4C)alkyl, (1-4C)haloalkylcarbamoyl(1-4C)alkyl, (1-3C)haloalkyl, (2-6C)hydroxyalkyl, (1-4C)alkoxy(2-4C)alkyl, (1-4C)alkylthio(2-4C)alkyl, (1-4C)alkanesulphinyl(1-4C)alkyl, (1-4C)alkanesulphonyl(1-4C)alkyl, (2-6C)aminoalkyl, (1-4C)alkylamino(1-6C)alkyl, (2-8C)dialkylamino(2-6C)alkyl, (1-5C)cyanoalkyl, 3-amino-3-carboxypropyl, 2-(amidinothio)ethyl, 2-(N-aminoamidinothio)ethyl, tetrahydropyran-2-yl, thietan-3-yl, 2-oxopyrrolidinyl, or 2-oxotetrahydrofuranyl, or R¹⁷ is of the formula IV:- -(CH₂) q -C(COOH)=CR¹⁸R¹⁹ (IV) wherein q is one or two and R¹⁸ and R¹⁹ are independently hydrogen or C₁₋₄alkyl; or R¹⁷ is of the formula V:- -CR²⁰R²¹-(CH₂) r -COR²² (V) wherein r is 0-3, R²⁰ is hydrogen, (1-3C)alkyl or methylthio, R²¹ is hydrogen, (1-3C)alkyl, (3-7C)cycloalkyl, cyano, carboxy, (2-5C)carboxyalkyl or methanesulphonylamino, or R²⁰ and R²¹ are joined to form, together with the carbon to which they are attached, a (3-7C)carbocyclic ring, and R²² is hydroxy, amino, (1-4C)alkoxy, (1-4C)alkylamino or of the formula NHOR²³ in which R²³ is hydrogen or (1-4C)alkyl; or R¹⁶ may be of the formula =CH.R²⁴ wherein R²⁴ is hydrogen, halogen, (1-6C)alkyl, (3-7C)cycloalkyl, (2-6C)alkenyl, (3-7C)cycloalkenyl, phenyl or benzyl. A compound according to claim 5 wherein R¹⁷ is 2-carboxyprop-2-yl. A compound according to claim 1 which is: 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-hydroxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-methoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-benzyloxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-carboxymethoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-benzyloxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-allyloxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-n-butoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, or 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-cinnamyl)benzoylaminomethyl)ceph-3-em-4-carboxylic acid. A pharmaceutical composition which comprises a compound according to any one of claims 1 to 7 and a pharmaceutically acceptable carrier. A process for preparing a compound according to claim 1 which process comprises: (a) reacting a cephalosporin compound having a 3-position substituent of the formula: -CH₂NHR¹ wherein R¹ is as defined in claim 1 with a compound of the formula (VI): wherein R², R³, X, Y, R¹² and n are as defined in claim 1 and L is a leaving group; or b) for compounds of the formula (III), reacting a compound of the formula (VII) with a compound of the formula (VIII) or a reactive derivative thereof: wherein R¹-R³, R¹², R¹⁴-R¹⁶, n, X, X¹ and Y are as defined in claim 5; or c) for compounds of the formula (III) wherein R¹⁶ is a group = NOR¹⁷, reacting a compound of the formula (IX): wherein R¹-R³, R¹², R¹⁴, R¹⁵, X¹, X, Y and n are as defined in claim 5, with a compound of the formula: R¹⁷ONH₂ wherein R¹⁷ is as hereinbefore defined in claim 5; or d) for compounds of the formula (III) wherein R¹⁶ is a group =NOR¹⁷ and R¹⁷ is other than hydrogen, reacting a compound of the formula (III) as hereinbefore defined wherein R¹⁶ is a group =NOH with compound of the formula (X): L¹ - R²⁵ (X) wherein L¹ is a leaving group and R²⁵ is a group R¹⁷ other than hydrogen; or e) for compounds of the formula (III) forming a group R¹⁴ by cyclising an appropriate precursor thereof: wherein any functional groups are optionally protected; and thereafter, if necessary: i) removing any protecting group, ii) for preparing in vivo hydrolysable esters, esterifying corresponding hydroxy groups, iii) converting compounds wherein X¹ is S to compounds wherein X¹ is sulphinyl and vice versa, iv) forming a pharmaceutically acceptable salt. A compound of the formula (VIA): wherein Z,X,Y,R²,R³,R¹² and n are as defined in claim 9. Claims for the following Contracting States: ES, GR A process for preparing a cephalosporin compound having a 3-position substituent of the formula (I): wherein: R¹ is hydrogen, C₁₋₆ alkyl optionally substituted by any of halo, hydroxy, C₁₋₆ alkoxy, carboxy, amino, cyano, C₁₋₆ alkanoylamino, phenyl or heteroaryl, or R¹ is C₂₋₆ alkenyl; R² is hydroxy or an in vivo hydrolysable ester thereof; R³ is hydroxy or an in vivo hydrolysable ester thereof; Z is CH or N; X is a group CR⁴, wherein R⁴ is hydrogen, optionally substituted C₁₋₆alkyl, aryl, arylC₁₋₆ alkyl, heteroaryl or heteroaryl C₁₋₆alkyl; Y is a group NOR⁵, NNR⁵¹R⁶, NR⁷ (when -X=Y is ortho to a hydroxy group) or CR⁸R⁹, wherein R⁵ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁵¹ is hydrogen, optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆alkenyl, optionally substituted C₃₋₇cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆alkanoyl, arylC₁₋₆alkanoyl, heteroarylC₁₋₆alkanoyl, optionally substituted C₂₋₆alkenoyl, optionally substituted C₃₋₇cycloalkylcarbonyl, arylcarbonyl, heteroarylcarbonyl, carbamoyl, C₁₋₆alkylcarbamoyl, arylcarbamoyl or arylC₁₋₆alkylcarbamoyl; R⁶ is hydrogen, C₁₋₆ alkyl or arylC₁₋₆alkyl; R⁷ is optionally substituted C₁₋₆alkyl, arylC₁₋₆alkyl, heteroaryl C₁₋₆ alkyl, optionally substituted C₂₋₆ alkenyl, optionally substituted C₃₋₇ cycloalkyl, aryl or heteroaryl; R⁸ and R⁹ are independently halogen, hydrogen, optionally substituted C₁₋₆ alkyl, arylC₁₋₆alkyl, heteroarylC₁₋₆alkyl, optionally substituted C₂₋₆ alkenyl, C₃₋₇ cycloalkyl, aryl, heteroaryl, optionally substituted C₁₋₆ alkanoyl, optionally substituted C₁₋₆ alkoxycarbonyl, carboxy, arylcarbonyl, heteroarylcarbonyl or aryl C₁₋₆ alkoxycarbonyl; or X = Y is a group -N=N-R¹⁰ or, when Z is N, X = Y is also a group -N=CR¹⁰R¹¹ wherein R¹⁰ is optionally substituted aryl and R¹¹ is hydrogen or C₁₋₆alkyl; R¹² is C₁₋₆alkyl, halo, hydroxy, hydroxy C₁₋₆alkyl, cyano, trifluoromethyl, nitro, amino, C₁₋₆alkylamino, di-C₁₋₆alkylamino, C₁₋₆alkanoyl, C₁₋₆alkoxy, C₁₋₆alkylthio, C₁₋₆alkanoyloxy, carbamoyl, C₁₋₆alkylcarbamoyl, di-C₁₋₆alkylcarbamoyl, carboxy, carboxy C₁₋₆alkyl, C₁₋₆alkoxycarbonylC₁₋₆alkyl, sulpho, sulphoC₁₋₆alkyl, C₁₋₆ alkanesulphonamido, C₁₋₆alkoxycarbonyl, C₁₋₆alkanoylamino, thioureido or amidino, and n is zero to 2: which process comprises reacting a cephalosporin compound having a 3-position substituent of the formula: -CH₂NHR¹ wherein R¹ is as defined hereinabove with a compound of the formula (VI): wherein R², R³, X, Y, R¹² and n are as defined hereinabove and L is a leaving group; wherein any functional groups are optionally protected; and thereafter, if necessary: i) removing any protecting group, ii) for preparing in vivo hydrolysable esters, esterifying corresponding hydroxy groups, iii) forming a pharmaceutically acceptable salt. A process for preparing a compound of the formula (III): or a salt or ester thereof wherein R¹, R², R³, n,Z,X,Y and R¹² are as defined in claim 1; X¹ is sulphur, oxygen, methylene or sulphinyl; R¹⁵ is hydrogen, methoxy or formamido; R¹⁴ is 2-aminothiazol-4-yl or 2-aminooxazol-4-yl each optionally substituted in the 5-position by fluorine, chlorine or bromine, or R¹⁴ is 5-aminoisothiazol-3-yl, 5-amino-1,2,4-thiadiazol-3-yl, 3-aminopyrazol-5-yl, 3-aminopyrazol-4-yl, 2-aminopyrimidin-5-yl, 2-aminopyrid-6-yl, 4-aminopyrimidin-2-yl, 2-amino-1,3,4-thiadiazol-5-yl or 5-amino-1-methyl-1,2,4-triazol-3-yl; R¹⁶ is of the formula =N.O.R¹⁷ (having the syn configuration about the double bond) wherein R¹⁷ is hydrogen, (1-6C)alkyl, (3-8C)cycloalkyl, (1-3C)alkyl(3-6C)cycloalkyl, (3-6C)cycloalkyl(1-3C)alkyl, (3-6C)alkenyl, optionally substituted by carboxy, (5-8C)cycloalkenyl, (3-6C)alkynyl, (2-5C)alkylcarbamoyl, phenylcarbamoyl, benzylcarbamoyl, (1- 4C)alkylcarbamoyl(1-4C)alkyl, di(1-4C)alkylcarbamoyl(1-4C)alkyl, (1-4C)haloalkylcarbamoyl(1-4C)alkyl, (1-3C)haloalkyl, (2-6C)hydroxyalkyl, (1-4C)alkoxy(2-4C)alkyl, (1-4C)alkylthio(2-4C)alkyl, (1-4C)alkanesulphinyl(1-4C)alkyl, (1-4C)alkanesulphonyl(1-4C)alkyl, (2-6C)aminoalkyl, (1-4C)alkylamino(1-6C)alkyl, (2-8C)dialkylamino(2-6C)alkyl, (1-5C)cyanoalkyl, 3-amino-3-carboxypropyl, 2-(amidinothio)ethyl, 2-(N-aminoamidinothio)ethyl, tetrahydropyran-2-yl, thietan-3-yl, 2-oxopyrrolidinyl, or 2-oxotetrahydrofuranyl, or R¹⁷ is of the formula IV:- -(CH₂) q -C(COOH)=CR¹⁸R¹⁹ (IV) wherein q is one or two and R¹⁸ and R¹⁹ are independently hydrogen or C₁₋₄alkyl; or R¹⁷ is of the formula V:- -CR²⁰R²¹-(CH₂) r -COR²² (V) wherein r is 0-3, R²⁰ is hydrogen, (1-3C)alkyl or methylthio, R²¹ is hydrogen, (1-3C)alkyl, (3-7C)cycloalkyl, cyano, carboxy, (2-5C)carboxyalkyl or methanesulphonylamino, or R²⁰ and R²¹ are joined to form, together with the carbon to which they are attached, a (3-7C)carbocyclic ring, and R²² is hydroxy, amino, (1-4C)alkoxy, (1-4C) alkylamino or of the formula NHOR²³ in which R²³ is hydrogen or (1-4C)alkyl; or R¹⁶ may be of the formula =CH.R²⁴ wherein R²⁴ is hydrogen, halogen, (1-6C)alkyl, (3-7C)cycloalkyl, (2-6C)alkenyl, (3-7C)cycloalkenyl, phenyl or benzyl: which process comprises: a) reacting a cephalosporin compound having a 3-position substituent of the formula: -CH₂NHR¹ wherein R¹ is as defined in claim 1 with a compound of the formula (VI) wherein R², R³, X, Y, R¹² and n are as defined in claim 1 and L is a leaving group; or b) reacting a compound of the formula (VII) with a compound of the formula (VIII) or a reactive derivative thereof: wherein R¹-R³, R¹², R¹⁴-R¹⁶, n, X, X¹ and Y are as defined hereinabove; or c) for compounds wherein R¹⁶ is a group = NOR¹⁷, reacting a compound of the formula (IX): wherein R¹-R³, R¹², R¹⁴, R¹⁵, X¹, X, Y and n are as defined hereinabove with a compound of the formula: R¹⁷ONH₂ wherein R¹⁷ is as hereinbefore defined; or d) for compounds wherein R¹⁶ is a group =NOR¹⁷ and R¹⁷ is other than hydrogen, reacting a compound of the formula (III) as hereinbefore defined wherein R¹⁶ is a group =NOH with compound of the formula (X): L¹ - R²⁵ (X) wherein L¹ is a leaving group and R²⁵ is a group R¹⁷ other than hydrogen; or e) forming a group R¹⁴ by cyclising an appropriate precursor thereof: wherein any functional groups are optionally protected; and thereafter, if necessary: i) removing any protecting group, ii) for preparing in vivo hydrolysable esters, esterifying corresponding hydroxy groups, iii) converting compounds wherein X′ is S to compounds wherein X′ is sulphinyl and vice versa, iv) forming a pharmaceutically acceptable salt. A process according to either claim 1 or claim 2 for preparing a compound wherein R² and R³ are both hydroxy. A process according to either claim 1 or claim 2 for preparing a compound wherein the cephalosporin compound has a 3-position substituent of the formula (II): wherein Z is -CH= or -N= and R¹³ is hydrogen, C₁₋₆alkyl, benzyl, carboxyC₁₋₆alkyl or allyl. A process according to either claim 1 or claim 2 for preparing a compound wherein the cephalosporin compound has a 3-position substituent of the formula (IIa): wherein Z is -CH= or -N= and R⁰ is phenyl or 2,4,6-trimethylphenol. A process according to either claim 1 or claim 2 for preparing a compound which is: 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-hydroxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-methoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-benzyloxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-carboxymethoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-benzoyloxyimino)benzylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-allyloxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-6-n-butoxyimino)benzoylaminomethyl)ceph-3-em-4-carboxylic acid, or 7-[2-(2-aminothiazol-4-yl)-2-((Z)-1-carboxy-1-methylethoxyimino)acetamido]-3-((3,4-dihydroxy-5-cinnamyl)benzoylaminomethyl)ceph-3-em-4-carboxylic acid. A process for preparing a pharmaceutical composition which comprises bringing into association a cephalosporin compound having a 3-position substituent as defined in claim 1 and a pharmaceutically acceptable carrier.

Inventors: ACTON DAVID GORDON, DAVIES DAVID HUW, POYSER JEFFREY PHILIP, ACTON, DAVID GORDON, DAVIES, DAVID HUW, POYSER, JEFFREY PHILIP
Applicants: ICI PLC, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1989
Main classification: C07D501
IPC codes: A61K31, C07D501, C07C281