Cephalosporin compounds

.beta.-lactam antibiotics of formula (I) or a salt thereof, wherein R.sup.1 is hydrogen, methoxy of formamido; R.sup.2 is an acyl group, in particular that of an antibacterially active cephalosporin; CO.sub.2 R.sup.3 is a carboxy group or a carboxylate anion, or R.sup.3 is a readily removable carboxy protecting group (such as a pharmaceutically acceptable in vivo hydrolysable ester group); R.sup.4 represents up to four substituents selected from alkyl, alkenyl, alkynyl, alkoxy, hydroxy, halogen, amino, alkylamino, acylamino, dialkylamino, CO.sub.2 R, CONR.sub.2, SO.sub.2 NR.sub.2 (where R is hydrogen or C.sub.1-6 alkyl), aryl and heterocyclyl, which may be the same or different and wherein any R.sup.4 alkyl substituent is optionally substituted by any other R.sup.4 substituent; X is S, SO, SO.sub.2, O or CH.sub.2 ; Y is S, SO or SO.sub.2 ; and m is 1 or 2, useful in the treatment of bacterial infections in humans and animals. ##STR1##

This application is a 371 of PCT/GB 92/02231 filed Dec. 01, 1992. 
This invention relates to novel .beta.-lactam containing compounds, their 
preparation and their use, and in particular to a novel class of 
cephalosporins. These compounds have antibacterial properties, and are 
therefore of use in the treatment of bacterial infections in humans and 
animals caused by a wide range of organisms. 
We have found a particular class of cephalosporins bearing a cyclic 
thio-ether substituent at the 3-position of the cephalosporin nucleus that 
possesses prolonged and high levels of antibacterial activity, and shows 
good absorption both parentally and orally, especially orally. 
The present invention provides a compound of formula (I) or a salt thereof: 
##STR2## 
wherein 
R.sup.1 is hydrogen, methoxy or formamido; 
R.sup.2 is an acyl group, in particular that of an antibacterially active 
cephalosporin; 
CO.sub.2 R.sup.3 is a carboxy group or a carboxylate anion, or R.sup.3 is a 
readily removable carboxy protecting group (such as a pharmaceutically 
acceptable in vivo hydrolysable ester group); R.sup.4 represents hydrogen 
or up to four substituents selected from alkyl, alkenyl, alkynyl, alkoxy, 
hydroxy, halogen, amino, alkylamino, acylamino, dialkyimino, CO.sub.2 R, 
CONR.sub.2, SO.sub.2 NR.sub.2 (where R is hydrogen or C.sub.1-6 alkyl), 
aryl and heterocyclyl, which may be the same or different and wherein any 
R.sup.4 alkyl substituent is optionally substituted by any other R.sup.4 
substituent; X is S,SO,SO.sub.2,O or CH.sub.2 ; Y is S, SO or SO.sub.2 ; 
and m is 1 or 2. 
The bonding carbon atom of the cyclic thio-ether moiety which links the 
ring to the cephalosporin nucleus is generally asymmetric. The present 
includes either stereoisomer, as well as mixtures of both isomers. 
In compounds of formula (I) wherein R.sup.1 is formamido, the formamido 
group can exist in conformations wherein the hydrogen atoms of the 
--NH--CHO moiety are cis- or trans-; of these the cis conformation 
normally predominates. 
Since the .beta.-lactam antibiotic compounds of the present invention are 
intended for use as therapeutic agents in pharmaceutical compositions, it 
will be readily appreciated that preferred compounds within formula (I) 
are pharmaceutically acceptable, i.e. are compounds of formula (Ia) or 
pharmaceutically acceptable salts or pharmaceutically acceptable in vivo 
hydrolysable esters thereof: 
##STR3## 
wherein R.sup.1, R.sup.2, R.sup.4, m and X are as defined with respect to 
formula (I) and the group CO.sub.2 R.sup.6 is CO.sub.2 R.sup.3 where 
CO.sub.2 R.sup.3 is a carboxy group or a carboxylate anion. 
Accordingly, the present invention provides a compound of formula (Ia) or a 
pharmaceutically acceptable salt or in vivo hydrolysable ester thereof, 
for use as a therapeutic agent, and in particular an in vivo hydrolysable 
ester thereof for use as an orally administrable therapeutic agent. 
The present invention further provides a compound of formula (Ia) or a 
pharmaceutically acceptable salt or in vivo hydrolysable ester thereof, 
for use in the treatment of bacterial infections, more particularly an in 
vivo hydrolysable ester thereof for use in the oral treatment of bacterial 
infections. 
The present invention also includes a method of treating bacterial 
infections in humans and animals which comprises the administration of a 
therapeutically effective amount of an antibiotic compound of this 
invention of the formula (Ia) or a pharmaceutically acceptable in vivo 
hydrolysable ester thereof, in particular the oral administration of a 
therapeutically effective amount of an in vivo hydrolysable ester. 
In addition, the present invention includes the use of a compound of 
formula (Ia) or a pharmaceutically acceptable salt or in vivo hydrolysable 
ester thereof, for the manufacture of a medicament for the treatment of 
bacterial infections, in particular the use of an in vivo hydrolysable 
ester for the manufacture of a medicament for the oral treatment of 
bacterial infections. 
Those compounds of the formula (I) wherein R.sup.3 is a readily removable 
carboxy protecting group other than a pharmaceutically acceptable in vivo 
hydrolysable ester or which are in non-pharmaceutically acceptable salt 
form are primarily useful as intermediates in the preparation of compounds 
of the formula (Ia) or a pharmaceutically acceptable salt or 
pharmaceutically acceptable in vivo hydrolysable ester thereof. 
Suitable readily removable carboxy protecting groups for the group R.sup.3 
include groups forming ester derivatives of the carboxylic acid, including 
in vivo hydrolysable esters. The derivative is preferably one which may 
readily be cleaved in vivo. 
It will be appreciated that also included within the scope of the invention 
are salts and carboxy-protected derivatives, including in vivo 
hydrolysable esters, of any carboxy groups that may be present as optional 
substituents in compounds of formula (I) or (Ia). Also included within the 
scope of the invention are acid addition salts of any amino group or 
substituted amino group that may be present as optional substituents in 
compounds of formula (I) or (Ia). 
Suitable ester-forming carboxyl-protecting groups are those which may be 
removed under conventional conditions. Such groups for R.sup.3 include 
benzyl, p-methoxybenzyl, benzoylmethyl, p-nitrobenzyl, 4-pyridylmethyl, 
2,2,2-trichloroethyl, 2,2,2-tribromoethyl, t-butyl, t-amyl, allyl, 
diphenylmethyl, triphenylmethyl, adamantyl, 2-benzyloxyphenyl, 
4-methylthiophenyl, tetrahydrofur-2-yl, tetrahydropyran-2-yl, 
pentachlorophenyl, acetonyl, p-toluenesulphonylethyl, methoxymethyl, a 
silyl, stannyl or phosphorus- containing group, an oxime radical of 
formula --N.dbd.CHR.sup.7 where R.sup.7 is aryl or heterocyclic, or an in 
vivo hydrolysable ester radical such as defined below. 
When used herein the term `aryl` includes phenyl and naphthyl, each 
optionally substituted with up to five, preferably up to three, groups 
selected from halogen, mercapto, C.sub.1-6 alkyl, phenyl, C.sub.1-6 
alkoxy, hydroxy(C.sub.1-6)alkyl, mercapto(C.sub.1-6)alkyl, halo(C.sub.1-6) 
alkyl, hydroxy, amino, nitro, carboxy, C.sub.1-6 alkylcarbonyloxy, 
alkoxycarbonyl, formyl, or C.sub.1-6 alkylcarbonyl groups. 
The terms `heterocyclyl` and `heterocyclic` as used herein include aromatic 
and non-aromatic, single and fused, rings suitably containing up to four 
hetero-atoms in each ring selected from oxygen, nitrogen and sulphur, 
which rings may be unsubstituted or substituted by, for example, up to 
three groups selected from halogen, (C.sub.1-6)alkyl, (C.sub.1-6)alkoxy, 
halo(C.sub.1-6)alkyl, hydroxy, carboxy, carboxy salts, carboxy esters such 
as (C.sub.1-6)alkoxycarbonyl, (C.sub.1-6)alkoxycarbonyl(C.sub.1-6)alkyl, 
aryl, and oxo groups. Each heterocyclic ring suitably has from 4 to 7, 
preferably 5 or 6, ring atoms. The term `heteroaryl` refers to 
heteroaromatic heterocyclic rings. A fused heterocyclic ring system may 
include carbocyclic rings and need include only one heterocyclic ring. 
Compounds within the invention containing a heterocyclyl group may occur 
in two or more tautometric forms depending on the nature of the 
heterocyclyl group; all such tautomeric forms are included within the 
scope of the invention. 
When used herein the terms `alkyl` alkenyl, alkynyl and `alkoxy` include 
straight and branched chain groups containing from 1 to 6 carbon atoms, 
such as methyl, ethyl, propyl and butyl. A particular alkyl group is 
methyl. 
When used herein the term `halogen` refers to fluorine, chlorine, bromine 
and iodine. 
A carboxyl group may be regenerated from any of the above esters by usual 
methods appropriate to the particular R.sup.3 group, for example, acid- 
and base- catalysed hydrolysis, or by enzymically-catalysed hydrolysis, or 
by hydrogenolysis under conditions wherein the remainder of the molecule 
is substantially unaffected. 
Examples of suitable pharmaceutically acceptable in vivo hydrolysable ester 
groups include those which break down readily in the human body to leave 
the parent acid or its salt. Suitable ester groups of this type include 
those of part formulae (i), (ii), (iii), (iv) and (v): 
##STR4## 
wherein R.sup.a is hydrogen, C.sub.1-6 alkyl, C.sub.3-7 cycloalkyl, 
methyl, or phenyl, R.sup.b is C.sub.1-6 alkyl, C.sub.1-6 alkoxy, phenyl, 
benzyl, C.sub.3-7 cycloalkyl, C.sub.3-7 cycloalkyloxy, C.sub.1-6 alkyl 
C.sub.3-7 cycloalkyl, 1-amino C.sub.1-6 alkyl, or 1-(C.sub.1-6 alkyl)amino 
C.sub.1-6 alkyl; or R.sup.a and R.sup.b together form a 1,2-phenylene 
group optionally substituted by one or two methoxy groups; R.sup.c 
represents C.sub.1-6 alkylene optionally substituted with a methyl or 
ethyl group and R.sup.d and R.sup.e independently represent C.sub.1-6 
alkyl; R.sup.f represents C.sub.1-6 alkyl; R.sup.g represents hydrogen or 
phenyl optionally substituted by up to three groups selected from halogen, 
C.sub.1-6 alkyl, or C.sub.1-6 alkoxy; Q is oxygen or NH; R.sup.h is 
hydrogen or C.sub.1-6 alkyl; R.sup.i is hydrogen, C.sub.1-6 alkyl 
optionally substituted by halogen, C.sub.2-6 alkenyl, C.sub.1-6 
alkoxycarbonyl, aryl or heteroaryl; or R.sup.h and R.sup.i together form 
C.sub.1-6 alkylene; R.sup.j represents hydrogen, C.sub.1-6 alkyl or 
C.sub.1-6 alkoxycarbonyl; and R.sup.k represents C.sub.1-8 alkyl, 
C.sub.1-8 alkoxy, C.sub.1-6 alkoxy(C.sub.1-6)alkoxy or aryl. 
Examples of suitable in vivo hydrolysable ester groups include, for 
example, acyloxyalkyl groups such as acetoxymethyl, pivaloyloxymethyl, 
.alpha.-acetoxyethyl, .alpha.-pivaloyloxyethyl, 
1-(cyclohexylcarbonyloxy)prop-1-yl, and (1-aminoethyl)carbonyloxymethyl; 
alkoxycarbonyloxyalkyl groups, such as ethoxycarbonyloxymethyl, 
.alpha.-ethoxycarbonyloxyethyl and propoxycarbonyloxyethyl; 
dialkylaminoalkyl especially di-loweralkylamino alkyl groups such as 
dimethylaminomethyl, dimethylaminoethyl, diethylaminomethyl or 
diethylaminoethyl; 2-(alkoxycarbonyl)-2-alkenyl groups such as 
2-(isobutoxycarbonyl)pent-2-enyl and 2-(ethoxycarbonyl)but-2-enyl; lactone 
groups such as phthalidyl and dimethoxyphthalidyl; and esters linked to a 
second .beta.-lactam antibiotic or to a .beta.-lactamase inhibitor. 
A preferred in vivo hydrolysable ester group is the pivaloyloxymethyl 
ester. 
A further suitable pharmaceutically acceptable in vivo hydrolysable ester 
group is that of the formula: 
##STR5## 
wherein R.sup.5 is hydrogen, C.sub.1-6 alkyl or phenyl. 
Suitable pharmaceutically acceptable salts of the carboxy group of the 
compound of formula (I) include metal salts, e.g. aluminium, alkali metal 
salts such as sodium or potassium, especially sodium, alkaline earth metal 
salts such as calcium or magnesium, and ammonium or substituted ammonium 
salts, for example those with lower alkylamines such as triethylamine, 
hydroxy-lower alkylamines such as 2-hydroxyethylamine, 
bis-(2-hydroxyethyl)amine or tris-(2-hydroxyethyl)- amine, 
cycloalkylamines such as dicyclohexylamine, or with procaine, 
dibenzylamine, N,N-dibenzylethylene- diamine, 1-ephenamine, 
N-methylmorpholine, N-ethylpiperidine, N-benzyl-.beta.-phenethylamine, 
dehydroabietylamine, N,N'-bisdehydro-abietylamine, ethylenediamine, or 
bases of the pyridine type such as pyridine, collidine or quinoline, or 
other amines which have been used to form salts with known penicillins and 
cephalosporins. Other useful salts include the lithium salt and silver 
salt. Salts within compounds of formula (I), may be prepared by salt 
exchange in conventional manner. 
In compounds of formula (I) or (Ia), the group X may be sulphur or an 
oxidised sulphur atom, i.e. a sulphoxide (SO) or sulphone (SO.sub.2) 
group. When X is a sulphoxide group it will be understood that .alpha.- 
and .beta.-isomers may exist; both such isomers are encompassed within the 
scope of the present invention. 
Examples of X include S, SO, SO.sub.2, O and CH.sub.2. Preferably X is 
sulphur or CH.sub.2. 
In compounds of formula (I) or (Ia), the group Y may be sulphur or an 
oxidised sulphur atom, i.e. a sulphoxide (SO) or sulphone (SO.sub.2) 
group. When Y is a sulphoxide group it will be understood that .alpha.- 
and .beta.-isomers may exist; both such isomers are encompassed within the 
scope of the present invention. 
Advantageously, R.sup.1 is hydrogen. 
Suitably, the cyclic thio-ether at the 3-position of the cephalosporin 
nucleus is unsubstituted or substituted by up to three substituents, 
R.sup.4, selected from C.sub.1-6 alkyl, for example methyl, C.sub.1-6 
alkoxy, for example methoxy, C.sub.1-6 alkoxycarbonyl for example 
methoxycarbonyl, C.sub.1-6 alkoxy C.sub.1-6 alkyl, for example 
methoxymethyl, and C.sub.1-6 alkanoyloxy C.sub.1-6 alkyl, for example 
acetoxymethyl. Preferably the cyclic thio-ether at the 3-position of the 
cephalosporin nucleus is unsubstituted. 
Preferably m is 1. 
Preferably the cyclic thio-ether is bonded to the cephalosporin nucleus at 
a ring carbon adjacent to the sulphur heteroatom. 
Suitable acyl groups R.sup.2 include those of formulae (a)-(f): 
##STR6## 
wherein p is 0, 1 or 2; m is 0, 1 or 2; A.sub.1 is C.sub.1-6 alkyl, 
substituted C.sub.1-6 alkyl, C.sub.3-6 cycloalkyl, cyclohexenyl, 
cyclohexadienyl, an aromatic (including heteroaromatic) group, such as 
phenyl, substituted phenyl, thienyl, pyridyl, or an optionally substituted 
thiazolyl group, a C.sub.1-6 akylthio group or C.sub.1-6 alkyloxy; X.sub.1 
is a hydrogen or halogen atom, a carboxylic acid, carboxylic ester, 
sulphonic acid, azido, tetrazolyl, hydroxy, acyloxy, amino, ureido, 
acylamino, heterocyclylamino, guanidino or acylureido group; A.sub.2 is an 
aromatic group, for example a phenyl, 
2,6-dimethoxyphenyl,2-alkoxy-1-naphthyl, 3-arylisoxazolyl, or a 
3-aryl-5-methylisoxazolyl group, such as 
3-(2-chloro-6-fluorophenyl)-5-methylisoxazol-4-yl; a substituted alkyl 
group; or a substituted dithietane; X.sub.2 is a --CH.sub.2 OCH.sub.2 --, 
--CH.sub.2 SCH.sub.2 -- or alkylene group; X.sub.3 is an oxygen or sulphur 
atom; A.sub.3 is an aryl or heteroaryl group such as phenyl, substituted 
phenyl, furyl, aminothiazolyl or aminothiadiazolyl in which the amino 
group is optionally protected; and A.sub.4 is hydrogen, C.sub.1-6 alkyl, 
C.sub.3-8 cycloalkyl, C.sub.3-8 cycloalkyl(C.sub.1-6)alkyl, C.sub.1-6 
alkoxycarbonyl(C.sub.1-6) alkyl, C.sub.2-6 alkenyl, 
carboxy(C.sub.1-6)alkyl, C.sub.2-6 alkynyl, aryl or C.sub.1-6 alkyl 
substituted by up to three aryl groups. 
The term `heteroaryl` as used herein means a heteroaromatic heterocyclic 
ring or ring system, suitably having 5 or 6 ring atoms in each ring. 
Suitably when R.sup.2 is a group (a), A.sub.1 is C.sub.1-6 alkyl, C.sub.3-6 
cycloalkyl, cyclohexenyl, cyclohexadienyl, phenyl, substituted phenyl such 
as hydroxyphenyl, thienyl or pyridyl; and X.sub.1 is a hydrogen or halogen 
atom, or a carboxy, carboxylic ester, azido, tetrazolyl, hydroxy, acyloxy, 
optionally protected amino, ureido, guanidino or acylureido group. 
Suitably when R.sup.2 is a group of formula (d), A.sub.2 is phenyl, X.sub.3 
is oxygen and p is O. 
Alternatively when R.sup.2 is a group of formula (e) or (f) suitable values 
for the group A.sub.3 include those commonly found in antibacterially 
active cephalosporins containing a hydroxyimino, substituted hydroxyimino 
or vinyl group in the side chain attached to position 7 of the 
cephalosporin nucleus, for example phenyl, thien-2-yl, thien-3-yl, 
fur-2-yl, fur-3-yl, pyrid-2-yl, pyrid-3-yl, pyrid-4-yl, 
5-amino-1,2,4-thiadiazol-3-yl and 2-aminothiazol-4-yl in each of which the 
amino group is optionally protected. 
Preferred groups for A.sub.3 include phenyl, 2-aminothiazol-4-yl, fur-2-yl, 
thien-2-yl, 2-(2-chloroacetamido)thiazol-4-yl, 2-tritylamino-thiazol-4-yl, 
5-_amino-1,2,4-thiadiazol-3-yl and 4-aminopyrimid-2-yl. 
In compounds of formula (Ia), a particularly preferred group for A.sub.3 is 
2-aminothiazol-4-yl. 
Suitable values for the group A.sub.4 include hydrogen, methyl, ethyl, 
cyclopropylmethyl, triphenylmethyl (trityl), cyclobutyl, cyclopentyl, 
cyclohexyl, cycloheptyl, cyclooctyl, phenyl, carboxymethyl, carboxypropyl 
and t-butoxycarbonylmethyl. 
Preferred values for A.sub.4 in compounds of formula (Ia) include methyl 
and hydrogen. 
It will be appreciated that compounds of the invention wherein R.sup.2 is a 
group of formula (e) (or (f)) can exist as syn and anti (or E and Z) 
isomers or mixtures thereof. Both isomers are encompassed within the scope 
of this invention. 
Preferably the compounds of the invention wherein R.sup.2 is a group of 
formula (e) have the sin configuration (i.e. have the group OA.sub.4 syn 
to the amide linkage) or are enriched in that isomer. 
Similarly, when R.sup.2 is a group of formula (f), the group A.sub.4 is 
preferably cis to the amide linkage, i.e. when group (f) is 
2-amino-thiazol-4-yl, the Z-configuration is preferred. 
Certain compounds of the invention include an amino group which may be 
protected. Suitable amino protecting groups are those well known in the 
art which may be removed under conventional conditions without disruption 
of the remainder of the molecule. 
Examples of amino protecting groups include C.sub.1-6 alkanoyl; benzoyl; 
benzyl optionally substituted in the phenyl ring by one or two 
substituents selected from C.sub.1-4 alkyl, C.sub.1-4 alkoxy, 
trifluoromethyl, halogen, or nitro; C.sub.1-4 alkoxycarbonyl; 
benzyloxycarbonyl or trityl substituted as for benzyl above; 
allyloxycarbonyl, trichloroethoxycarbonyl or chloroacetyl. 
Some of the compounds of this invention may be crystallised or 
recrystallised from solvents such as organic solvents. In such cases 
solvates may be formed. This invention includes within its scope 
stoichiometric solvates including hydrates as well as compounds containing 
variable amounts of water that may be produced by processes such as 
lyophilisation. 
Since the antibiotic compounds of the invention are intended for use in 
pharmaceutical compositions it will readily be understood that they are 
each provided in substantially pure form, for example at least 60% pure, 
more suitably at least 75% pure and preferably at least 85%, especially at 
least 95% pure (% are on a weight for weight basis). Impure preparations 
of the compounds may be used for preparing the more pure forms used in the 
pharmaceutical compositions; these less pure preparations of the compounds 
should contain at least 1%, more suitably at least 5% and preferably from 
10 to 49% of a compound of the formula (I) or salt thereof. 
Specific compounds within this invention of formula (Ia) include the 
following pharmaceutically acceptable carboxylic adds, salts and in-vivo 
hydrolysable esters: 
sodium 
(6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(Z)-methoxyiminoacetamido]-3-[(RS)-te 
trahydrothien-2-yl]-ceph-3-em-4-carboxylate; 
pivaloyloxymethyl 
(6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(Z)-methoxyiminoacetamido]-3-[(RS)-te 
trahydrothien-2yl-]ceph-3-em-4-carboxylate; and 
sodium 
(6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(Z)-methoxyiminoacetamido]-3-[1,1-dio 
xotetrahydrothien-2-yl]-ceph-3-em-4-carboxylate 
The present invention further provides a process for the preparation of a 
compound of formula (I), which process comprises treating a compound of 
formula (II) or a salt thereof: 
##STR7## 
wherein R.sup.1, CO.sub.2 R.sup.3, R.sup.4, m, X and Y are as hereinbefore 
defined, wherein any reactive groups may be protected, and wherein the 
amino group is optionally substituted with a group which permits acylation 
to take place; with an N-acylating derivative of an acid of formula (III): 
EQU R.sup.2 OH (III) 
wherein R.sup.2 is as defined with respect to formula (I) and wherein any 
reactive groups may be protected; and thereafter, if necessary or desired, 
carrying out one or more of the following steps: 
i) removing any protecting groups; 
ii) converting the group CO.sub.2 R.sup.3 into a different group CO.sub.2 
R.sup.3 ; 
iii) converting the group R.sup.2 into a different group R.sup.2 ; 
iv) converting the group X into a different group X; 
v) converting the product into a salt. 
Acids of formula (III) may be prepared by methods known in the art, or 
methods analogous to such processes. Suitable processes include those 
described, for example, in UK Patent 2 107 307 B, UK Patent Specification 
No. 1,536,281, and U.K. Patent Specification No. 1,508,064. 
Suitable groups which permit acylation to take place and which are 
optionally present on the amino group of the starting material of the 
formula (II) include N-silyl, N-stannyl and N-phosphorus groups, for 
example trialkylsilyl groups such as trimethylsilyl, trialkyltin groups 
such as tri-n-butyltin, groups of formula --P.R.sup.20 R.sup.21 wherein 
R.sup.20 is an alkyl, haloalkyl, aryl, aralkyl, alkoxy, haloalkyl, aryl, 
aralkyl, alkoxy, haloalkoxy, aryloxy, aralkyloxy or dialkylamino group, 
R.sup.21 is the same as R.sup.20 or is halogen or R.sup.20 and R.sup.21 
together form a ring; suitable such phosphorus groups being --P(OC.sub.2 
H.sub.5).sub.2, --P(C.sub.2 H.sub.5).sub.2, 
##STR8## 
A group which may optionally be introduced onto the amino group in the 
compound of formula (II) is trimethylsilyl. 
Advantageously the silylation reaction may be carried out in situ, prior to 
the acylation reaction, with a silylating agent that does not require 
concomitant addition of base. Suitable silylating agents include, for 
example, N-(trimethylsilyl)-acetamide, N,O-bis-(trimethylsilyl)acetamide, 
N,O-bis(trimethylsilyl)- trifluoroacetamide, 
N-methyl-N-trimethylsilylacetamide, 
N-methyl-N-trimethylsilyl-trifluoroacetamide, 
N,N'-bis(trimethylsilyl)urea, and N,O-bis(trimethylsilyl)carbamate. A 
preferred silylating agent is N,O-bis(trimethylsilyl)acetamide. The 
silylation reaction may suitably be carried out in an inert, anhydrous 
organic solvent such as dichloromethane at room temperature or at an 
elevated temperature, for example 30.degree.-60.degree. C., preferably 
40.degree.-50.degree. C. 
The above process may optionally be carried out in the presence of a small 
quantity, for example 0.1 equivalents, of a silyl halide, for example a 
tri(C.sub.1-6)alkylsilyl halide, especially trimethylsilyl chloride. 
A reactive N-acylating derivative of the acid (III) is employed in the 
above process. The choice of reactive derivative will of course be 
influenced by the chemical nature of the substituents of the acid. 
Suitable N-acylating derivatives include an add halide, preferably the add 
chloride or bromide or alternatively a symmetrical or mixed anhydride. The 
acylation may be effected in the presence of an add binding agent for 
example, tertiary amine (such as pyridine or dimethylaniline), molecular 
sieves, an inorganic base (such as calcium carbonate or sodium 
bicarbonate) or an oxirane, which binds hydrogen halide liberated in the 
acylation reaction. The oxirane is preferably a (C.sub.1-6)-1,2-alkylene 
oxide--such as ethylene oxide or propylene oxide. The acylation reaction 
using an acid halide may be carried out at a temperature in the range 
-50.degree. C. to +50.degree. C., preferably -20.degree. C. to +20.degree. 
C., in aqueous or non-aqueous media such as water, acetone, 
tetrahydrofuran, ethyl acetate, dimethylacetamide, dimethylformamide, 
acetonitrile, dichloromethane, 1,2-dichloroethane, or mixtures thereof. 
Alternatively, the reaction may be carried out in an unstable emulsion of 
water-immiscible solvent, especially an aliphatic ester or ketone, such as 
methyl isobutyl ketone or butyl acetate. The acylation with add halide or 
anhydride is suitably carried out in the presence of a basic catalyst such 
as pyridine or 2,6-lutidine. 
Acid halides may be prepared by reacting the acid (III) or a salt or a 
reactive derivative thereof with a halogenating (e.g. chlorinating or 
brominating) agent such as phosphorus pentachloride, thionyl chloride, 
oxalyl chloride or phosgene. 
Suitable mixed anhydrides are anhydrides with, for example, carbonic acid 
monoesters, trimethyl acetic acid, thioacetic acid, diphenylacetic acid, 
benzoic acid, phosphorus acids (such as phosphoric, phosphorous, and 
phosphinic acids) or aromatic or aliphatic sulphonic acids (such as 
p-toluenesulphonic acid or methanesulphonic acid). 
Alternative N-acylating derivatives of acid (III) are the acid azide, or 
activated esters such as esters with 2-mercaptopyridine, cyanomethanol, 
p-nitrophenol, 2,4-dinitrophenol, thiophenol, halophenols, including 
pentachlorophenol, monomethoxyphenol, N-hydroxy succinimlde, 
N-hydroxybenzotriazole, or 8-hydroxyquinoline; or amides such as 
N-acylsaccharins, N-acylthiazolidin-2-thione or N-acylphthalimides; or an 
alkylidene iminoester prepared by reaction of the acid (III) with an 
oxime. 
Other reactive N-acylating derivatives of the acid (III) include the 
reactive intermediates formed by reaction in situ with a condensing agent 
such as a carbodiimide, for example, N,N'-diethyl-, dipropyl- or 
diisopropylcarbodiimide, N,N'-di-cyclohexyl-carbodiimide, or 
N-ethyl-N'-[3-(dimethylamino)propyl]- carbodiimide; a suitable carbonyl 
compound, for example, N,N'-carbonyldiimidazole or 
N,N'-carbonylditriazole; an isoxazolinium salt, for example, 
N-ethyl-5-phenylisoxazolinium-3-sulphonate or 
N-t-butyl-5-methylisoxazolinium perchlorate; or an N-alkoxycarbonyl 
2-alkoxy-1,2-dihydroquinoline, such as N-ethoxycarbonyl 
2-ethoxy-1,2-dihydroquinoline. Other condensing agents include Lewis acids 
(for example BBr.sub.3 --C.sub.6 H.sub.6); or a phosphoric acid condensing 
agent such as diethylphosphorylcyanide. The condensation reaction is 
preferably carried out in an organic reaction medium, for example, 
methylene chloride, dimethylformamide, acetonitrile, alcohol, benzene, 
dioxan or tetrahydrofuran. 
A further method of forming the N-acylating derivative of the add of 
formula (III) is to treat the add of formula (III) with a solution or 
suspension preformed by addition of a carbonyl halide, preferably oxalyl 
chloride, or a phosphoryl halide such as phosphorus oxychloride, to a 
halogenated hydrocarbon solvent, preferably dichloromethane, containing a 
lower acyl tertiary amide, preferably N,N-dimethylformamide. The 
N-acylating derivative of the acid of formula (III) so derived may then be 
caused to react with a compound of formula (II). The acylation reaction 
may conveniently be carried out at -40.degree. to +30.degree. C., if 
desired in the presence of an add binding agent such as pyridine. A 
catalyst such as 4-dimethylaminopyridine may optionally also be added. A 
preferred solvent for the above acylation reaction is dichloromethane. The 
optional reduction step, the optional conversion of R.sup.2 to a different 
R.sup.2, CO.sub.2 R.sup.3 to a different CO.sub.2 R.sup.3 and X to a 
different X,Y to a different Y, and the optional formation of a salt, may 
be carded out using methods well known in the art of cephalosporin and 
penicillin chemistry. 
For example, when the group X is S, SO, or SO.sub.2, the group X may be 
converted into a different group X by methods of oxidation or reduction 
well known in the art of cephalosporin and penicillin synthesis, as 
described, for example, in European Patent Application Publication No. 0 
114 752. Equally, when the group Y is S, SO, or SO.sub.2, the group Y may 
be converted into a different group Y by similar methods. For example, 
sulphoxides (in which X or Y is SO) may be prepared from the corresponding 
sulphide (in which X or Y is S) by oxidation with a suitable oxidising 
agent, for example an organic peracid such as m-chloroperbenzoic acid. 
A reduction step is generally effected by processes well known in the art 
of .beta.-lactam chemistry, for example using phosphorus trichloride in 
dimethylformamide. 
In the process described hereinabove, and in the process described 
hereinbelow, it may be necessary to remove protecting groups. Deprotection 
may be carded out by any convenient method known in the art such that 
unwanted side reactions are minimised. Separation of unwanted by-products 
may be carried out using standard methods. 
In a further process of the invention, compounds of formula (I) may be 
prepared by cyclising a compound of formula (IV): 
##STR9## 
wherein X, R.sup.1, R.sup.2, R.sup.4, and m, and CO.sub.2 R.sup.3 are as 
hereinbefore defined and P' is a phosphorus residue; and thereafter if 
necessary or desired, carrying out one or more of the following steps: 
i) removing any protecting groups; 
ii) converting the group CO.sub.2 R.sup.3 into a different group CO.sub.2 
R.sup.3 ; 
iii) converting the group R.sup.2 into a different group R.sup.2 ; 
iv) converting the group X into a different group X; 
v) converting the product into a salt. 
The cyclisation reaction is an intramolecular Wittig-type reaction and is 
typically carried out by heating the compound of formula (IV) in an 
organic solvent system, for example in toluene, optionally in the presence 
of a suitable add such as benzoic add. 
The phosphorus residue, P' is typically a trialkylphosphoranylidene 
residue, for example a C.sub.1-6 trialkylphosphoranylidene residue such as 
tri-n-butylphosphoranylidene, or a triarylphosphoranylidene residue such 
as triphenylphosphoranylidene. 
Where R.sup.2 in a compound of formula (I) is required to be different from 
the group R.sup.2 in the compound of formula (IV), the conversion may be 
effected via the intermediacy of a compound of formula (II) which has an 
amino group at the 7-position of the cephalosporin nucleus. 
An R.sup.2 acyl side-chain may be removed by the Delft procedure commonly 
used in .beta.-lactam chemistry. Suitable reaction conditions include 
treatment with phosphorus pentachloride and N-methylmorpholine at reduced 
temperature. 
Compounds of formula (II) are novel compounds and as such form part of the 
invention. 
A compound of formula (IV) may be prepared from a compound of formula (V): 
##STR10## 
wherein X, R.sup.1, R.sup.2, R.sup.4, m, and CO.sub.2 R.sup.3 are as 
hereinbefore defined, by reaction with a halogenating agent, suitably a 
chlorinating agent such as thionyl chloride, which reaction displaces the 
formula (V) hydroxyl group by halogen, suitably chloride, and is typically 
carried out at reduced temperature in an inert solvent, for example in 
tetrahydrofuran, in the presence of a base, typically a pyridine 
derivative such as 2,6-lutidine. Formation of the phosphorane may be 
effected by treatment of the halo-intermediate with an appropriate 
phosphine derivative, for example tri-n-butylphosphine or 
triphenylphosphine, suitably at ambient temperature in an inert solvent 
such as dioxan. 
A compound of formula (V) may be prepared by reaction of a compound of 
formula (VI): 
##STR11## 
wherein X, R.sup.1, R.sup.2, R.sup.4, and m are as hereinbefore defined 
with an ester of glyoxylic acid (OCHCO.sub.2 R.sup.3) in the presence of 
triethylamine. 
In a typical preparation of a compound of formula (VI) in which X is 
sulphur, a compound of formula (VII): 
##STR12## 
wherein Z is a leaving group and R.sup.4, and m are as hereinbefore 
defined is reacted with a compound of formula (VIII): 
##STR13## 
wherein R.sup.1 and R.sup.2 are as hereinbefore defined. 
Suitably, a leaving group Z is halogen, for example chloro. The reaction 
may be carried out at ambient temperature in an inert solvent, for example 
acetone or dimethylformamide, in the presence for a base, for example 
potassium carbonate. 
A compound of formula (V) may also be prepared by reaction of a compound of 
formula (IX): 
##STR14## 
wherein R.sup.1, R.sup.2 and CO.sub.2 R.sup.3 are as hereinbefore defined 
and X' is an X-group precursor, with a compound of formula (VII) as 
hereinbefore defined. 
In a typical preparation of a compound of formula (V) in which X is 
sulphur, a Z leaving group in a compound of formula (VII), suitably a 
halogen such as chloro or bromo, is displaced by an X' mercapto group in a 
compound of formula (IX). The reaction may be carried out at ambient 
temperature in an inert solvent, for example acetone, with the addition of 
base, for example potassium carbonate, before work-up. 
Azetidin-2-one compounds of formulae (VIII) and (IX) may be prepared 
according to known methods in heterocyclic synthetic chemistry and 
particularly by known methods in the art of .beta.-lactam chemistry. For 
example a compound of formula (VIII) may be prepared according to the 
method of Osborne N. F. et al., J. Chem. Soc., Perkin Trans. I, 146, 1980. 
A compound of formula (IX) in which X' is a mercapto group may be prepared 
by ring opening of a 4-thia-2,6-diazabicyclo [3.2.0]-hept-2-ene-7-one 
derivative according to the method of Masayuki Narisada et al., 
Tetrahedron Lett., 1755 (1978). 
Compounds of formula (VII) are known compounds or may be prepared by 
standard methodology. For example, the compounds of formula (VII) in which 
Y is chloro or bromo may be prepared from the corresponding carboxylic add 
(Y.dbd.COOH) via formation of the acid chloride followed by treatment with 
diazomethane and reaction of the resulting diazo compound with hydrogen 
chloride or hydrogen bromide. 
In a further process of the invention, compounds of formula (I) may be 
prepared directly by organo-cuprate displacement of a leaving group at the 
3-position of a compound of formula (X): 
##STR15## 
wherein R.sup.1, R.sup.2, CO.sub.2 R.sup.3 and X are as hereinbefore 
defined and L is a leaving group, suitably a mesylate, triflate or 
fluorosulphonate leaving group, by reaction with a compound of formula 
(XI): 
##STR16## 
wherein Z' is an organo-cuprate group and R.sup.4 and m are as 
hereinbefore defined. 
A compound with a 3-position leaving group, L, in which X is sulphur may be 
prepared by the procedure of Farina V. et al., J. Org. Chem., 54, 4962, 
(1989). 
A compound with a 3-position leaving group, L, in which X is CH.sub.2 may 
be prepared by a transition metal-catalysed carbenoid insertion reaction 
of a diazodicarbonyl compound of formula (XII): 
##STR17## 
wherein R.sup.1, R.sup.2 and CO.sub.2 R.sup.3 are as hereinbefore defined, 
followed by reaction with an appropriate anhydride, for example triflic 
anhydride. 
Compounds of formula (XII) may be prepared by the procedure of Bodurow C. 
and Carr M. A.; Tetrahedron Lett., 30 4801, (1989). 
It should be noted that in processes of this invention .DELTA..sup.2 
-cephems may function as intermediates, in the synthetic sequences. 
Subsequent isomerisation steps by methods well known in cephalosporin 
chemistry will provide the .DELTA..sup.3 -cephems of the invention. 
The present invention also provides a pharmaceutical composition which 
comprises a compound of formula (Ia) or a pharmaceutically acceptable salt 
or in vivo hydrolysable ester thereof and a pharmaceutically acceptable 
carrier. The compositions of the invention include those in a form adapted 
for oral, topical or parenteral use and may be used for the treatment of 
bacterial infection in mammals including humans. 
The antibiotic compounds according to the invention may be formulated for 
administration in any convenient way for use in human or veterinary 
medicine, by analogy with other antibiotics. 
The composition may be formulated for administration by any route, such as 
oral, topical or parenteral, especially oral. The compositions may be in 
the form of tablets, capsules, powders, granules, lozenges, creams or 
liquid preparations, such as oral or sterile parenteral solutions or 
suspensions. 
The topical formulations of the present invention may be presented as, for 
instance, ointments, creams or lotions, eye ointments and eye or ear 
drops, impregnated dressings and aerosols, and may contain appropriate 
conventional additives such as preservatives, solvents to assist drug 
penetration and emollients in ointments and creams. 
The formulations may also contain compatible conventional carders, such as 
cream or ointment bases and ethanol or oleyl alcohol for lotions. Such 
carders may be present as from about 1% up to about 98% of the 
formulation. More usually they will form up to about 80% of the 
formulation. 
Tablets and capsules for oral administration may be in unit dose 
presentation form, and may contain conventional excipients such as binding 
agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or 
polyvinylpyrollidone; fillers, for example lactose, sugar, maize-starch, 
calcium phosphate, sorbitol or glycine; tabletting lubricants, for example 
magnesium stearate, talc, polyethylene glycol or silica; disintegrants, 
for example potato starch; or acceptable wetting agents such as sodium 
lauryl sulphate. The tablets may be coated according to methods well known 
in normal pharmaceutical practice. Oral liquid preparations may be in the 
form of, for example, aqueous or oily suspensions, solutions, emulsions, 
syrups or elixirs, or may be presented as a dry product for reconstitution 
with water or other suitable vehicle before use. Such liquid preparations 
may contain conventional additives, such as suspending agents, for example 
sorbitol, methyl cellulose, glucose syrup, gelatin, hydroxyethyl 
cellulose, carboxymethyl cellulose, aluminium stearate gel or hydrogenated 
edible fats, emulsifying agents, for example lecithin, sorbitan 
monooleate, or acacia; non-aqueous vehicles (which may include edible 
oils), for example almond oil, oily esters such as glycerine, propylene 
glycol, or ethyl alcohol; preservatives, for example methyl or propyl 
p-hydroxybenzoate or sorbic acid, and, if desired, conventional flavouring 
or colouring agents. 
Suppositories will contain conventional suppository bases, e.g. 
cocoa-butter or other glyceride. 
For parenteral administration, fluid unit dosage forms are prepared 
utilizing the compound and a sterile vehicle, water being preferred. The 
compound, depending on the vehicle and concentration used, can be either 
suspended or dissolved in the vehicle. In preparing solutions the compound 
can be dissolved in water for injection and filter sterilised before 
filling into a suitable vial or ampoule and sealing. 
Advantageously, agents such as a local anaesthetic, preservative and 
buffering agents can be dissolved in the vehicle. To enhance the 
stability, the composition can be frozen afar filling into the vial and 
the water removed under vacuum. The dry lyophilized powder is then sealed 
in the vial and an accompanying vial of water for injection may be 
supplied to reconstitute the liquid prior to use. Parenteral suspensions 
are prepared in substantially the same manner except that the compound is 
suspended in the vehicle instead of being dissolved and sterilization 
cannot be accomplished by filtration. The compound can be sterilised by 
exposure to ethylene oxide before suspending in the sterile vehicle. 
Advantageously, a surfactant or wetting agent is included in the 
composition to facilitate uniform distribution of the compound. 
The compositions may contain from 0.1% by weight, preferably from 10-60% by 
weight, of the active material, depending on the method of administration. 
Where the compositions comprise dosage units, each unit will preferably 
contain from 50-500 mg of the active ingredient. The dosage as employed 
for adult human treatment will preferably range from 100 to 3000 mg per 
day, for instance 1500 mg per day depending on the route and frequency of 
administration. Such a dosage corresponds to 1.5 to 50 mg/kg per day. 
Suitably the dosage is from 5 to 20 mg/kg per day. 
No unacceptable toxicological effects are expected when a compound of 
formula (Ia) or a pharmaceutically acceptable salt or in vivo hydrolysable 
ester thereof is administered in the above-mentioned dosage range. 
The compound of formula (Ia) may be the sole therapeutic agent in the 
compositions of the invention or a combination with other antibiotics or 
with a .beta.-lactamase inhibitor may be employed. 
Advantageously, the compositions also comprise a compound of formula (XIII) 
or a pharmaceutically acceptable salt or ester thereof: 
##STR18## 
wherein 
A is hydroxyl, substituted hydroxyl, thiol, substituted thiol, amino, mono- 
or di-hydrocarbyl- substituted amino, or mono- or di-acylamino; an 
optionally substituted triazolyl group; or an optionally substituted 
tetrazolyl group as described in EP-A-0 053 893. 
A further advantageous composition comprises a compound of formula (Ia) or 
a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof 
together with a compound of formula (XIV) or a pharmaceutically acceptable 
salt or in vivo hydrolysable ester thereof: 
##STR19## 
wherein 
B represents hydrogen, halogen or a group of formula: 
##STR20## 
in which R.sup.8 and R.sup.9 are the same or different and each represents 
hydrogen, C.sub.1-6 alkoxycarbonyl or carboxy, or a pharmaceutically 
acceptable salt thereof. 
Further suitable .beta.-lactamase inhibitors include 6-alkylidene penems of 
formula (XV): 
##STR21## 
or a pharmaceutically acceptable salt or in vivo hydrolysable ester 
thereof, wherein R.sup.10 and R.sup.11 are the same or different and each 
represents hydrogen, or a C.sub.1-10 hydrocarbon or heterocyclic group 
optionally substituted with a functional group; and R.sup.12 represents 
hydrogen or a group of formula R.sup.13 or --SR.sup.13 where R.sup.13 is 
an optionally substituted C.sub.1-10 hydrocarbon or heterocyclic group, as 
described in EP-A-0 041 768. 
Further suitable .beta.-lactamase inhibitors include 
6.beta.-bromopenicillanic acid and pharmaceutically acceptable salts and 
in vivo hydrolysable esters thereof and 6.beta.-iodopenicillanic acid and 
pharmaceutically acceptable salts and in vivo hydrolysable esters thereof 
described in, for example, EP-A-0 410 768 and EP-A-0 154 132 (both Beecham 
Group). 
Such compositions of this invention which include a .beta.-lactamase 
inhibitory amount of a .beta.-lactamase inhibitor are formulated in a 
conventional manner using techniques and procedures per se known in the 
art. 
The antibiotic compounds of the present invention are active against a wide 
range of organisms including both Gram-negative organisms such as E. coli 
and Gram-positive organisms such as S. aureus.