GB2052981A - Penicillanic acid derivatives as beta -lactamase inhibitors - Google Patents

Abstract

Compounds of formula (I): <IMAGE> and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof, wherein n is 0 or 2, R<1> is C1-6 alkyl optionally substituted with one, two or three fluorine, chlorine or bromine atoms, or is di-C1-6 alkylamino or is a group of formula (i): <IMAGE> wherein X is a bond, or -CH = CH-, or methylene or ethylene; R<2> is hydrogen, fluorine, bromine or chlorine, or is amino, protected amino, hydroxy, protected hydroxy, C1-6 alkyl, nitro, di-C1-6 alkylamino, acetamido, C1-6 alkoxy or trifluromethyl; R<3> is hydrogen or chlorine or C1-6 alkyl or trifluoromethyl; and R<4> is hydrogen or chlorine, or C1-6 alkyl or C1-6 alkoxy; or R<2> and R<3> on any two adjacent carbon atoms may together represent a buta-1,3-dienylene moiety which is optionally substituted by C1-3 alkyl or C1-3 alkoxy, are beta - lactamase inhibitors and may be used in combination with penicillins and cephalosporins.

Description

SPECIFICATION Penicillanic acid derivatives, their preparation and use This invention relates to a class of penicillanic acid derivatives which are useful as sslactamase inhibitors.

Certain GP-sulphonyloxypenicillanic acids are known (Sheehan et al. Cambridge symposium on sslactam antibiotics June 1976; and USP 4143046]. However in the past these compounds have only been disclosed as having anti-bacterial activity, which has proved disappointing. No mention has been made that any of these compounds might possess fi-lactamase inhibitory properties. Surprisingly, it has been found that these and related compounds possess the ability to enhance the effectiveness of penicillins and cephalosporins.

The present invention provides a pharmaceutical composition comprising: (a) a pharmaceutically acceptable carrier; (b) a compound of the formula (I):

and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof, wherein n is 0 or 2, R' is a C16 alkyl group optionally substituted with one, two or three fluorine, chlorine or bromine atoms, or is a di-C1 6 alkylamino group or is a group of the formula (i):

wherein X is a bond, or a -CH = CH group, or a methylene or ethylene group; R2 is a hydrogen, fluorine, bromine or chlorine atom, or is an amino, protected amino, hydroxy, protected hydroxy, C16 alkyl, nitro, di-C1 6 alkylamino, acetamido, C1-6 alkoxy or trifluromethyl group;R3 is a hydrogen or chlorine atom or a C16 alkyl or trifluoromethyl group; and R4 is a hydrogen or chlorine atom, or a C18 alkyl or C18 alkoxy group; or R2 and R3 on any two adjacent carbon atoms may together represent a buta-1,3-dienylene moiety which is optionally substituted by a C13 alkyl or C13 alkoxy group; and (c) a penicillin or cephalosporin or a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof.

When the terms protected amino" and "protected hydroxy" are used in this specification, the groups used herein for protecting these functions are those that may be removed when desired; for example any of such group known in the art, such as a benzyloxycarbonyl, pnitrobenzyloxycarbonyl or benzyl group.

Preferably n is zero.

Suitably R' is a C16 alkyl group optionally substituted with one, two or three fluorine, chlorine or bromine atoms.

More suitably R' is a methyl, ethyl, propyl, chloropropyl or isopropyl group.

In compounds of the formula (i) suitably X is a bond or a methylene group.

Apt values for R2 include the hydrogen, fluorine, chlorine and bromine atoms, and amino, protected amino, hydroxy, protected hydroxy, C1-6 alkyl, nitro, C1-6 alkylamino, acetamido, C1-6 alkoxy and trifluoromethyl groups.

Suitably R2 is a hydrogen, fluorine, bromine or chlorine atom, or a methyl or methoxy group.

A preferred value of R2 is methyl.

A further preferred value of R2 is bromine.

Apt values for R3 are a hydogen or chlorine atom, or a C18 alkyl or trifluoromethyl group.

Suitably R3 is a hydrogen or chlorine atom.

A preferred value for R3 is hydrogen.

Apt values for R4 are a hydrogen or chlorine atom, or a C18 alkyl group.

Suitably R4 is a hydrogen or chlorine atom.

A preferred value for R4 is hydrogen.

Thus it is to be realised that a particularly suitable sub-group of the compounds for use in the compositions of this invention is that of the formula (ill):

and pharmaceutically acceptable salts and in-vivo hydrolysable esters thereof, wherein R2, R3 and R4 are as herein before defined.

Preferably in the compounds of the formula (li) R3 and R4 are both hydrogen atoms and R2 is selected from hydrogen, bromine, fluorine, chlorine, C18 alkyl nitro and amino. Most favourably R3 and R4 are both hydrogen and R2 is hydrogen, methyl, bromine or amino.

Preferably also in the compounds od the formula (II) R2 and R3 are on any two adjacent carbon atoms and represent a buta-1,3-dienylene moiety, thus forming a naphthyl group.

Suitably also in the compounds of the formula (II) R2, R3 and R4 are all methyl groups.

The compounds of the formulae (I)-(ll) are suitably provided in the form of the free acid.

Alternatively the compounds of the formulae (I)-(ll) are provided in the form of a pharmaceutically acceptable salt.

Examples of pharmaceutically acceptable salts of the compounds of the formulae (I)-(ll) include the alkali metal salts such as sodium or potssium, 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, tris-(hydroxymethyl)amine or tris-(2-hydroxyethyl)-amine, cycloalkylamines such as bicyclohexylamine, or with procaine, dibenzylamine, N,N-dibenzylethylenediamine, 1-ephenamine, N-ethyl-piperidine, N-benzyl-ss-phenethylamine, dehydroabietyl-amine or N,N'-bis-dehydroabietylethylenediamine.

Thus suitable salts of this invention include the sodium, potassium, calcium, magnesium and ammonium salts, of these the sodium, potassium and calcium salts are favoured.

The compounds of the formulae (I)-(ll) may be provided as in-vivo hydrolysable esters. Such esters are those which hydrolyse in the human body to produce the parent acid. Suitable in-vivo hydrolysable esters include those esters known to give in-vivo hydrolysis in penicillins. Thus suitable esters include those of the formula (ii): -CO-O-CHR,-O-CO-R2 (ii) wherein R1 is a hydrogen atom, or a methyl or phenyl group; R2 is an alkyl group of 1 to 6 carbon atoms, a phenyl group, an alkyl group of 1 to 3 carbon atoms substituted by a phenyl group, an alkoxy group of 1 to 6 carbon atoms, a phenoxy group, or an alkoxy group of 1 to 3 carbon atoms substituted by a phenyl group; or R, is attached to R2 to form a 1 ,2-diphenylene or 4, 5-dimethoxy-1 ,2-diphenylene group.

Favourably R, is hydrogen.

When R1 is hydrogen suitably R2 is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, phenyl, benzyl, methoxy, ethoxy, n-propyloxy and isopropyloxy. Preferably R2 is tertbutyl.

Favourably R, and R2 are joined so that the ester is a phthalidyl or 3,4-dimethoxyphthalidyl ester.

Of these esters those favoured as in-vivo hydrolysable esters are the acetoxymethyl, acetoxye thyl, phthalidyl, ethoxycarbonyloxymethyl, a-ethoxycarbonyloxyethyl and pivaloyloxymethyl esters.

The in-vivo hydrolysable nature of the ester may be confirmed by administration to an animal such as a mouse or rat and determination of the presence of a compound of the formula (I) or a salt thereof in the blood or urine of the animal. Alternatively hydrolysis in human blood or serum may be determined.

It must be realised that salts of the compounds of the formulae (I)-(ll) formed with pharmaceutically unacceptable ions are useful as they may serve as intermediates in the preparation of pharmaceutically acceptable salts by ion-exchange, or they may be useful as intermediates in the preparation of in-vivo hydrolysable esters. An example of such a salt is the lithium salt.

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 the infection in mammals including humans.

Suitable forms of the compositions of this invention include tablets, capsules, creams, syrups, suspensions, solutions, reconstitutable powders and sterile forms suitable for injection or infusion. Such compositions may contain conventional pharmaceutically acceptable materials such as diluents, binders, colours, flavours, preservatives, disintegrant and the like in accordance with conventional pharmaceutical practice in the manner well understood by those skilled in the art of formulating antibiotics.

Injectable or infusable compositions of a compound of the invention are particularly suitable as high blood levels of the compound can occur after administration by injection or infusion.

Thus, one preferred composition aspect of this invention comprises a compound of the invention in sterile form and most suitably in sterile crystalline form.

The injectable solution of the compound of this invention may be made up in a sterile pyrogen-free liquid such as water, aqueous ethanol or the like.

This invention also provides the use of a penicillin or cephalosporin or pharmaceutically acceptable salt or in-vivo hydrolysable ester thereof in composition with a compound of the formula (I) or pharmaceutically acceptable salt or in-vivo hydrolysable ester thereof, for preparing injectable aqueous solutions.

Such solutions may be prepared by dissolving the sterile compound of this invention and the penicillin or cephalosporin in sterile water. Suitably this water is "Water for Injection BP" or the equivalent and may contain electrolytes to render it isotonic.

A particularly suitable injectable aqueous solution of this invention is one which contains not less than 15% w/w of the salt of the compound of the formula (I).

Unit dose compositions comprising a compound of this invention adapted for oral administration form a further suitable composition aspect of this invention.

Orally administrable compositions are of use as a synergistically effective blood level can be expected at high dose and at lower doses such compositions may be used to treat infections localised in the gastro-intestinal tract.

Unit dose compositions comprising a compound of this invention adapted for topical administration are also presented by this invention. In this instance 'topical administration' also includes local administration to internal surfaces of mammary glands of cattle, for example during the treatment of mastitis by intramammary administration. Considerable advantages accrue from the inclusion of a penicillin or cephalosporin since the resulting composition shows enhanced effectiveness (synergy).

Suitable penicillins for inclusion in the compositions of this invention include benzylpenicillin, phenoxymethylpenicillin, carbenicillin, azidocillin, propicillin, ampicillin, amoxycillin, epicillin, ticarcillin, cyclacillin, pirbenicillin, azlocillin, mezlocillin, celbenicillin and other known penicillins including pro-drugs therefore such as their in-vivo hydrolysable esters such as the acetoxymethyl, pivaloyloxymethyl, a-ethoxy-carbonyloxyethyl or phthalidyl esters of ampicillin, benzylpenicillin or amoxycillin, and aldehyde or ketone adducts of penicillins containing a 6-a-aminoacetamide side chain (such as hetacillin, metampicillin and analogous derivatives of amoxycillin) or a-esters of carbenicillin or ticarcillin such as their phenyl or indanyl a-esters.

Suitable cephalosporins for inclusion in the compositions of this invention include cefatrizine, cephaloridine, cephalothin, cefazolin, cephalexin, cephacetrile, cephamandole nafate, cephapirin, cepradine, 4-hydroxycephalexin, cefaprole, cephaloglycin, and other known cephalosporins or pro-drugs thereof.

Such compounds are frequently used in the form of a salt for example the sodium, potassium or calcium salt or a hydrate thereof.

Naturally if the penicillin or cephalosporin present in the composition is not suitable for oral administration then the composition will be adapted for parenteral administration. As previously indicated such injectable or infusable compositions can be particularly apt.

Highly favoured penicillins for use in the compositions of this invention include ampicillin, amoxycillin, carbenicillin and ticarcillin. Such penicillins may be used as a pharmaceutically acceptable salt such as the sodium salt.

Alternatively the ampicillin or amoxycillin may be used in the form of fine particles of the zwitterionic form (generally as ampicillin trihydrate or amoxycillin trihydrate) for use in an injectable suspension, for example, in the manner herein before described for a composition of this invention.

The preferred penicillin for use in the synergistic composition is amoxycillin, for example as its sodium salt or trihydrate.

Particularly suitable cephalosporins for use in the compositions of this invention include cephaloridine and cefazolin.

When present together with a cephalosporin or penicillin, the ratio of a compound of the invention to the penicillin or cephalosporin agent may vary over a wide range of ratios, such as from 10:1 to 1:10 for example about 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5 or 1:6, (wt/wt, based on pure free antibiotic equivalent).

The total quantity of a compound of the formula (I) or its pharmaceutically acceptable salt or in vivo hydrolysable ester in any unit dosage will normally be between 25 and 1000 mg and will usually be between 50 and 500 mg, for example about 62.5, 100, 125, 150, 200 or 250 mg.

Compositions of this invention may be used for the treatment of infections inter alia, the respiratory tract, the urinary tract and soft tissues in humans and mastitis in cattle.

Normally between 50 and 1000 mg of a synergist will be administered each day of treatment but more usually as 2, 3 or 4 doses.

The penicillin or cephalosporin in the synergistic composition of this invention will normally be present at approximately the amount at which it is conveniently used which will usually be expected to be from about 62.5 to 1000 mg per dose, more usually about 125, 250 or 500 mg per dose.

One particularly favoured composition of this invention will contain from 1 50 to 1000 mg of amoxycillin as the trihydrate or sodium salt and from 25 to 500 mg of a synergist.

Most suitably this form of composition will contain a pharmaceutically acceptable salt of the compound of the formula (I).

A further particularly favoured composition of this invention will contain from 1 50 to 1000 mg of ampicillin or a pro-drug therefor and from 25 to 500 mg of a synergist.

Most suitably this form of composition will contain ampicillin trihydrate, ampicillin anhydrate, sodium ampicillin, hetacillin, pivampicillin hydrochloride bacampicillin hydrochloride or talampicillin hydrochloride. Most suitably this form of the composition will contain a compound of the formula (I) or its pharmaceutically acceptable salt.

Most suitably the preceding compositions will contain from 200 to 700 mg of the penicillin component. Most suitably the preceding composition will comprise from 50 to 250 mg of a compound of the formula (I).

Such compositions may be adapted for oral or parenteral use except when containing an in vivo hydrolysable ester of ampicillin or amoxycillin in which case the compositions will not be adapted for parenteral administration.

Another particularly favoured composition of this invention will contain from 200 to 2000 mg of carbenicillin, ticarcillin or a pro-drug therefor and from 50 to 500 mg of a synergist.

Suitably this form of composition will contain di-sodium carbenicillin. Suitably this form of the composition will contain di-sodium ticarcillin.

Most suitably this form of the composition will contain from 75 to 250 mg of a compound of the formula (I) or pharmaceutically acceptable salt or in vivo hydrolysable ester thereof preferably in crystalline form. Such compositions containing di-salts of carbenicillin and ticarcillin will be adapted for parenteral administration.

The present invention also provides a method of treating bacterial infections in humans or domestic mammals which comprises the administration of a composition of this invention.

Commonly the infection treated will be due to a strain of Staphylococcus aureus, Escherichia coli or Proteus sp. The organisms named are readily treated by using a synergistically effective amount of the synergist and a penicillin or cephalosporin. The administration of the two components may take place separately but in general we prefer to use a composition containing both the synergist and the penicillin or cephalosporin.

The indications for treatment include respiratory tract and urinary tract infections in humans and mastitis in cattle.

The present invention also provides the compounds of the formula (I) or pharmaceutically acceptable salts or in vivo hydrolysable esters thereof with the proviso that when n is 0, then R is not methyl, benzyl, p-chlorobenzyl, phenyl or p-aminophenyl when the compounds of this invention are in the form of a free acid or a pharmaceutically acceptable salt.

Suitable classes of groups and novel compounds of this invention are those described above in relation to the compounds of the formula (I) and (II) for use in the compositions of this invention.

The compounds of the formula (I) or salts or esters thereof may be prepared by the reaction of a compound of the formula (III), or a derivative thereof which allows acylation to taken place:

wherein n is O or 2 and Rx is a hydrogen atom or a carboxy protecting group, with an O- sulphonating derivative of a compound of the formula (IV): R'S03H (IV) wherein R' is as hereinbefore defined in relation to formula (I); and thereafter if desired, (a) cleaving the carboxy protecting group to form the free acid or salt thereof.

(b) converting the free acid or salt into a pharmaceutically acceptable salt or in-vivo hydrolysable ester, (c) converting the compound wherein n is O to the compound where n is 2.

Suitable O-sulphonating derivatives include R'SO2CI, R'SO2Br and (R'SO2)2O; of these the sulphonyl chloride is preferred.

Suitable groups Rx include the hydrogen atom, in-vivo hydrolysable esters as hereinbefore described, and conventional protecting groups well-known to those skilled in the art of penicillin chemistry. Such conventional protecting groups include salts and ester derivatives of the carboxylic acid.

The derivative is preferably one which may readily be cleaved at a later stage of the reaction.

Suitable salts include sodium, potassium, dicyclohexylamine and tertiary amine salts, such as those with tri-lower-alkylamines, N-ethylpiperidine, 2,6-lutidine, pyridine, N-methylpyrrolidine, dimethylpiperazine. A preferred salt is with triethylamine.

Suitable ester-forming carboxyl-protecting groups are those which may be removed under conventional conditions. Such groups for Rx include benzyl, p-methoxybenzyl, 2,4,6-trimethylbenzyl, 3,5-di-t-butyl-4-hydroxybenzyl, benzoylmethyl, p-nitrobenzyl, 4-pyridylmethyl, 2,2,2trichloroethyl, 2,2,2-tribromoethyl, t-butyl, t-amyl, diphenylmethyl, triphenylmethyl, adamantyl, 2-benzyloxyphenyl, 4-methylthiophenyl, tetrahydrofuran-2-yl, tetrahydropyran-2-yl, pentachlorophenyl, p-toluenesulphonylethyl, methoxymethyl, a silyl group such as trimethylsilyl, a stannyl or phosphorus-containing group, or an oxime radical of formula -N = CHR' where R" is aryl or heterocyclic.

The carboxyl group may be regenerated from any of the above esters by usual methods appropriate to the particular Rx group, or by enzymatically-catalysed hydrolysis, or by hydrogenaction.

Suitably the reaction of a compound of the formula (III) with a compound of the formula (IV) is performed in the presence of an organic or inorganic base. More suitably the base is an organic amine such as a tri-C, 6 alkylamine or pyridine. Preferably the base is triethylamine.

Inorganic bases may be used for example sodium hydroxide, potassium hydroxide or sodium hydride.

Suitably the reaction of an ester of a compound of the formula (III) and a compound of the formula (IV) as hereinbefore described is performed in an inert organic solvent, for example diethylether, tetrahydrofuran, dioxan, 1, 2-dimethoxyethane, chloroform, dichloromethane, ethyl acetate, acetone and acetonitrile.

A particularly suitable solvent is dichloromethane.

The reaction of an inorganic salt of a compound of the formula (III) such as the sodium or potassium salt and a compound of the formula (IV) is suitably performed in an aqueous solvent system. The reaction of an organic amine salt of a compound of the formula (III) and a compound of the formula (IV) is suitably performed in a chlorinated solvent, for example dichloromethane.

Suitably the reaction is performed at a temperature between - 30" and 30 . A particularly preferred procedure is to commence the reaction at 0 C and permit the reaction temperature to rise slowly to ambient.

Since it is frequently desirable to form a salt of the compound of the formula (I), it is a preferred embodiment to use as the carboxyl protecting group in the compounds of the formula (III) an ester that is readily converted to the parent acid or its salt by mild methods of hydrogenolysis. Particularly suitable esters for use in this process include benzyl esters optionally substituted by C1s alkyl, C18 alkoxy, bromine, chlorine or nitro. A preferred ester is the benzyl ester.

Suitable methods of hydrogenation include hydrogenation in the presence of a transition metal catalyst. The pressure of hydrogen used in the reaction may be low, medium or high but in general an approximately atmospheric or slightly super-atmospheric pressure of hydrogen is preferred. The transition metal catalyst employed is preferably palladium on charcoal or on calcium carbonate. The hydrogenation may be effected in any inert solvent in which the ester is soluble for example tetrahydrofuran, ethyl acetate, methanol, ethanol, and mixtures thereof together with water. If this hydrogenation is carried out in the presence of a base then a salt of the compound of the formula (I) is produced. Suitable bases for inclusion include NaHCO3, KHC03, Na2CO3, CaCO3, MgCO3, LiHC03, NH4OCOCH3 and the like.If no base is present then hydrogenation leads to the preparation of an acid within formula (I) which may then be neutralised if desired to yield a salt. Suitable bases which may be used to neutralise acids within formula (I) include LiOH, NaOH, NaHCO3, KOH, Ca(OH)2 and Ba(OH)2.

The salts of acids (I) may be converted to esters in conventional manner, for example by reaction with a reactive halide such as bromomethyloxy pivalate in solution in dimethylformamide.

The substituent group or groups within the groups R2 and R3 in the compounds of formula (I) may be varied by conventional reactions. Thus for example when a substituent is a nitro group it may be reduced in a conventional manner to an amino group, for example by catalysed hydrogenation. Similarly an amino group may be acylated to give a substituted amino group, for example by treatment with an acyl halide in the presence of an organic base. Substituents such as NHCO2p-nitro-benzyl of OCO2p-nitrobenzyl may be converted to an amino or hydroxyl group respectively for example by hydrogenolysis.

The compounds of the formula (III) and derivatives thereof wherein n is 0 are described in United States Patent No 4,143,046 which is herein incorporated by reference.

The compounds of formula (I) wherein n is 2, and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof may be prepared by treatment of the corresponding compound of the formula (I) wherein n is 0 with an oxidising agent in an inert solvent at a non-extreme temperature, for example 0"-30"C.

A suitable oxidising agent is m-chloroperbenzoic acid.

When the oxidising agent used is m-chloroperbenzoic acid suitable solvents include water, diethyl ether, tetrahydrofuran, dioxan, ethyl acetate, chloroform and dichloromethane. Preferred solvents are dichloromethane, diethyl ether and chloroform.

In analogous manner the compounds of the formula (III) wherein n is 2 may be prepared from compounds of the formula (III) wherein n is 0.

The following Examples illustrate the invention.

Example 1 Calcium 6fi-p-brnmobenzenesulphonyloxypeniciiianate Benzyl 6ss-hydroxypenicillanate (0.202 g) was dissolved in chloroform (3 ml) containing dimethylformamide (0.15 ml), and to this stirred solution was added p-bromobenzene-sulphonyl chloride (0.255 g) and triethylamine (0.092 ml). After 24 hours the reaction mixture was diluted with chloroform (20 ml), washed with dilute sodium bicarbonate (15 ml), washed with water (15 ml), dried (MgSO4), and evaporated in vacuo to afford a gum. This gum was subjected to rapid column chromatography on silica gel (20 g) using ethyl acetate: cyclohexane (1 :3).The appropriate fractions were combined and evaporated in vacuo to afford an oil, which was crystallised from ethyl acetate-cyclohexane to yield benzyl 6ss-bromobenzenesulphonyloxy- penicillanate as white crystals, m.p. 117-118"C; i.r. (Nujol) 1795, 1755, 1745 cm~'; n.m.r.

(CDCl3) 1.36(3H, s), 1.56(3H, s), 4.45(1H, s), 5.15(2H, s), 5.47(1H, d J=4Hz), 5.65(1H, d J= 4Hz), 7.35(5H, s), 7.77(4H, ABq J= 9Hz).

Benzyl 6fi-p-bromobenzenesulphonyloxypenicillanate (0.097 g) was dissolved in a solvent mixture of tetrahydrofuran (3 ml), methanol (3 ml), and water (3 ml), and was hydrogenated over 5% Palladium on calcium carbonate (0.3 g) for 1 hour. The catalyst was filtered off and washed liberally with water and methanol. The combined filtrates were concentrated in vacuo to afford the title compound as a white solid (0.09 g), i.r. (KBr) 3400, 1778, 1595cm-1; n.m.r.

(D20) 1.38(3H, s), 1.49(3H, s), 4.19(1H, s), 5.37 (1H, d J=4.5Hz), 5.87(1H, d J=4.5Hz), 7.5-8.1(4H, m).

Example 2 Sodium GP-ethanesulphonyloxypenicillanate To a solution of benzyl 6ss-hydroxypenicillanate (0.5 g) in dichloromethane (10 ml) containing triethylamine (0.4 ml) at - 1 0'C was added ethanesulphonyl chloride (0.2 ml). The solution was stirred at - 1 0'C for 15 min., then washed with iced water, dilute hydrochloric acid, sodium bicarbonate, brine and finally dried over anhydrous magnesium sulphate.Removal of the solvent in vacuo yielded benzyl 6fi-ethanesulphonyloxypenicillanate as a pale yellow oil (0.57 g), may (CHCl3) 1800, 1750, 1500, 1460, 1370, 1300, 1280, 1180, 850 and 840 cm-1; [a]2D0 + 173.3 (c 1.2% CHCl3), 8 (CDCI3) 7.35 (5H, s, ArH), 5.75 (1H, d, J= 3.7Hz, H-C6), 5.52 (1H, d, J= 3.7Hz, H-C5), 5.17 (2H, s, CH2-Ph), 4.50 (1H, s, H-C3), 3.28 (2H, q, J= 7.4Hz, Me-CH2-S), 1.63 (3H, s, gem CH3), 1.46 (3H, t, J-7.4Hz, CH3-CH2-S), 1.43 (3H, s, gem CH3).

Benzyl 6ss-ethanesulphonyloxypenicillanate (0.2 g) was dissolved in tetrahydrofuran (10 ml) containing water (3 drops) and 10% palladium-carbon catalyst (0.4 g). The mixture was hydrogenolysed at atmospheric pressure for < hr, then filtered (celite) and evaporated in vacuo.

The resulting oil was partitioned between ethyl acetate: water and neutralised with sodium hydroxide (0.5 M). The aqueous layer was separated and the water removed in vacuo to yield sodium 6ssethanesulphonyloxypenicillanate as a pale brown solid (0. 108 g), may (KBr) 1750, 1610, 1520, 1430, 1360, 1240, 1170,89Oand86Ocm1;(ciY0= +219.4 (c1.2H20),8 (D20) 5.92 (1H, d, J= 3.7 Hz, H-C5), 5.61 (1H, d, J= 3.7Hz, H-Cs), 4.27 (1H, s, H-C3), 3.46 (2H, q, Me-CH2-S), 1.56 (3H, s, gem CH3), 1.45 (3H, s, gem CH3), 1.35 (3H, t, C H3-CH2-S).

Example 3 Sodium 6ss-(2-naphthalenesulphonyloxy)penicillanate To a solution of benzyl 6ss-hydroxypenicillanate (0.6 g) in pyridine (10 ml) was added 2naphthalenesulphonyl chloride (0.8 g). The solution was allowed to stand at 4"C for 24 hr., and then poured on to iced water, and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was then washed with dilute sulphuric acid (2 X 40 ml) and dried over anhydrous sodium sulphate-sodium carbonate.Removal of the solvent in vacuo yielded benzyl 6ss-(2-naphthalene- sulphonyloxy)penicillanate as a pale yellow oil (0.5 g), VmaX (CHCl3) 1800, 1750, 1460, 1180, and 900 cm-'; 8 (CDCI3) 7.55 (7H, m, ArH), 7.35 (5H, s, ArH ester), 5.70 (1H, d, J=4Hz,H- C6), 5.45 (1H, d, j=4Hz, H-C5), 5.15 (2H, s, CH2-Ph), 4.45 (1H, s, H-C3), 1.55 (3H, s, gem CH3), 1.35 (3H, s, gem CH3).

Benzyl 6fl-(2-naphthalenesulphonyloxy)penicillanate (0.4 g), was dissolved in tetrahydrofuran (15 ml) containing water (3 drops) and 10% palladium-carbon catalyst (0.8 g). The mixture was hydrogenolysed at atmospheric pressure for + hr, then filtered (celite) and the solvent evaporated in vacuo. The resulting oil was partitioned between ethyl acetate : water and neutralised with sodium hydroxide (0.5 M).The aqueous layer was separated and freeze dried to yield sodium 6ss(2-naphthalenesulphonyloxy)-penicillanate as a white solid, s'm,x (KBr), 1785, 1610, 1410, 1390, 1230, 1185 and 900 cm-1; #(D2O) 8.65 (1H, s, ArH), 8.00 (6H, m, ArH), 6.05 (1 H, d, J= 3.8Hz, H-C5), 5.55 (1 H, d, J= 3.8Hz, H-C5), 4.23 (1 H, s, H-C3), 1.60 (3H, s, gem CH3), 1.50 (3H, s, gem CH3).

Example 4 Sodium 6fi-mesitylenesulphonyloxypenicillanate To a solution of benzyl 6ss-hydroxypenicillanate (0.64 g) in pyridine (10 ml) was added mesitylenesulphonyl chloride (0.5 g). The solution was allowed to stand at 4"C for 24 hr. then poured on to iced water and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was then washed with dilute sulphuric acid (2 X 20 ml) and dried over anhydrous sodium sulphate-sodium carbonate.Removal of the solvent in vacuo yielded benzyl 6ss-mesitylenesul- phonyloxypenicillanate (0.8 g), may (CHCl3) 1790, 1740, 1600, 1190 and 880 cm-; 8 (d5-DMS0) 7.40 (5H, s, ArH), 7.15 (2H, s, ArH), 5.85 (1 H, d, J= 3.8Hz, H-C5), 5.48 (1 H, d, J= 3.8Hz, H-C5), 5.20 (2H, s, CH2Ph), 4.55 (1 H, s, H-C3), 2.60 (6H, s, ArCH3), 2.30 (3H, s, ArCH3), 1.55 (3H, s. gem CH3), 1.35 (3H, s, gem CH3).

Benzyl 6ss-mesitylenesulphonyloxypenicillanate (0.45 g) was dissolved in tetrahydrofuran (15 ml) containing water (3 drops) and 10% palladium-carbon catalyst (0.9 g). The mixture was hydrogenolysed at atmospheric pressure for + hr. then filtered (celite) and the solvent evaporated in vacuo. The resulting oil was partitioned between ethyl acetate : water-and neutralised with sodium hydroxide (0.5 M). The aqueous layer was separated and freeze dried to yield sodium 6ss-mesitylenesulphonyloxypenicillanate as a white solid (0.39 g), "max (KBr), 1780, 1600, 1190 and 850 cm~'; 8 (D20) 6.90 (2H, s, ArH), 5.62 (1 H, d, J= 3.8Hz, H-C5), 5.30 (1 H, d, J= 3.8Hz, H-C5), 4.05 (1 H, s, H-C3), 2.35 (6H, s, ArCH3), 2.05 (3H, s, ArCH3), 1.35 (3H, s, gem CH3), 1.25 (3H, s, gem CH3).

Example 5 Sodium 6ss(p-bromobenzenesulphonyloxy)penicillanate To a solution of benzyl 6sshydroxypenicillanate (1.2 g) in pyridine (20 ml) was added pbromobenzenesulphonyl chloride (2 g). The solution was allowed to stand at 4"C for 24 hr. then poured on to iced water and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was then washed with dilute sulphuric acid (2 X 100 ml) and dried over anhydrous sodium sulphate-sodium carbonate. Removal of the solvent in vacuo yielded benzyl GP-(p-bromobenzen- esulphonyloxy)penicillanate as an orange brown solid which was purified by reprecipitation from ethyl acetate at - 70"C by the addition of light petrol, to give an off white solid (1.6 g).

Benzyl 6ss-(p-bromobenzenesulphonyloxy)penicillanate (0.6 g) was dissolved in tetrahydrofuran (15 ml) containing water (3 drops) and 10% palladium-carbon catalyst (1.2 g). The mixture was hydrogenolysed at atmospheric pressure for + hr then filtered (celite) and the solvent removed.

The resulting oil was partitioned between ethyl acetate : water and neutralised with sodium hydroxide (0.5 M). The aqueous layer was separated and the water removed under reduced pressure to yield a pale brown solid (0.36 g), vmax (KBr) 1775, 1610, 1090 and 890cm-1; S (D20) 7.80 (4H, m, ArH) 5.90 (1H, d, J= 4Hz, H-Cs), 5.40 (1H, d, J= 4Hz, H-C5), 4.19 (1H, s, H-C3), 1.55 (3H, s, gem CH3), 1.40 (3H, s, gem CH3).

Example 6 Sodium 6fi-(p-toluenesulphonyloxy)peniclllanate 1,1-dioxide To a solution of benzyl GP-hydroxypenicillanate 1, 1-dioxide (0.5 g) in pyridine (15 ml) of O"C was added p-toluenesulphonyl chloride (0.6 g). The solution was allowed to stand at 4"C for 24 hr then poured on to iced water and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was washed with dilute sulphuric acid (2 x 20 ml) and finally dried over sodium sulphate-sodium carbonate.Removal of the solvent in vacuo yielded benzyl 6ss-(p-toluenesul- phonyloxy)penicillanate 1,1-dioxide as a pale yellow oil (0.58 g), 3'm,x (CHCl3), 1820, 1750, 1600 cm-; 8 (CDC13) 7.88 (2H, m, ArH), 7.35 (7H, m, Ar, 5.80 (1H, d, J= 4Hz, H-C6), 5.20 (2H, q, CH2-Ph), 4.75 (1 H, d, J = 4Hz, H-C5), 4.50 (1 H, s, H-C3), 2.44 (3H, s, ArCH3), 1.23 (3H, s, gem CH3).

Benzyl GP-(p-toluenesulphonyloxy)penicilianate 1 ,1-dioxide (0.2 g) was dissolved in tetrahydrofuran (10 ml) containing water (3 drops) and 10% palladium-carbon catalyst (0.4 g). The mixture was hydrogenolysed at atmospheric pressure for + hr then filtered (celite). Removal of the solvent in vacuo from the filtrate yielded a colourless glass which was dissolved in ethyl acetate (1 ml) to which solution 2M sodium 2-ethyl hexanoate in methyl isobutyl ketone (0.13 ml) was added.Sodium GP-(p-toluene-sulphonyloxy)penicillanate 1,1-dioxide was precipitated from the solution by addition of diethyl ether (20 ml), as a white solid (0.14 g), Vmax (KBr), 1800, 1620, 1460 and 1180cm-1; S(D20) 7.60 (4H, m, ArH), 6.03 (1H, d, J= 4Hz, H-C5), 5.10 (1H, d, J= 4Hz, H-C5), 4.32 (1H, s, H-C3), 2.39 (3H, s, ArCH3), 1.50 (3H, s, gem CH3), 1.35 (3H, s, gem CH3).

Example 7 Lithium 6ss(p-toluenesulphonyloxy)penicillanate Benzyl 6ss-hydroxypenicillanate (0.2029) was dissolved in chloroform (4ml) containing dimethylformamide (0.1 5 ml). To this stirred solution at 0 C was added p-toluenesulphonyl chloride (0.087 g) and triethylamine (0.092 ml). The reaction mixture was allowed to warm to room temperature. After 48 hours, the reaction mixture was diluted with chloroform (20 ml), washed with dilute sodium bicarbonate (20 ml), washed with water (20 ml), dried (MgSO4), and evaporated in vacuo to afford an oil.This oil was subjected to column chromatography on silica gel (20 g) using ethyl acetate:cyclohexane (1:3). The appropriate fractions were combined and evaporated in vacuo to afford the title compound as a gum, which was crystallised from ethyl acetate-cyclohexane to yield benzyl 6ss-(p-toluenesulphonyloxy)penicillanate as white crystals (0.09 g) m.p. 97"C; i.r. (Nujol) 1790, 1757 cm~1; n.m.r. (CDCl3) 1.37(3H, s), 1.57(3H, s), 2.45 (3H, s), 4.46(1 H, s), 5.16(2H, s), 5.45(1 H, d J= 4Hz), 5.62(1 H, d J=4Hz), 7.35(5H, s), 7.60(4H, ABq J= 9Hz).

Benzyl 6fl-(p-toluenesulphonyloxy)penicillanate (0.078 g) in tetrahydrofuran (15 ml) was hydrogenated over 10% palladium-carbon catalyst (0.12 g) for 4 hr. The mixture was then filtered (celite), evaporated to 1 ml and water (5 ml) added. The resulting solution was titrated to pH 7.0 with LiOH and the solvent removed to yield, after washing with ether, lithium 6ss-(p- toluenesulphonyloxy)penicillanate as a pinkish white solid (0.055 g), #max (KBr), 1780, 1610, 1195, 1180 cm-; (D20) 7.75 (2H, d, J= 8Hz, ArH), 7.34 (2H, d, J= 8Hz, ArH), 5.84 (1H, d, J= 3Hz, H-C5), 5.37 (1 H, d, J = 3Hz, H-C5),4.19(1H,s, H-C3), 2.32 (3H, s, ArH), 1.49 (3H, s, gem CH3), 1.39 (3H, s, gem CH3).

Example 8 Sodium 6fi-(p-nitrobenzenesulphonyloxylpeniclllana te To a solution of sodium GP-hydroxypenicillanate (0.78 g) in dimethylformamide was added methoxymethyl chloride (0.65 ml). The solution was stirred at 0 C for 15 min then poured on to iced water and extracted with ethyl acetate (3 X 30 ml). The ethyl acetate layer was separated, washed with water, dried over anhydrous magnesium sulphate, and the solvent removed in vacuo.The resulting oil was chromatographed on silica gel (ethylacetate : petrol) to yield methoxymethyl 6ss-hydroxypenicillanate (0.51 g), may (CHCl3) 1790, 1760, 1400, 1160 cm-', S(CDCl3) 5.58 (1H, d, J=4Hz, H-C5), 5.13 (1H, d, J=4 Hz, H-C5), 5.30 (2H, s, CH2O), 3.49 (3H, s, CH3O), 1.67 (3H, s, gem CH3), 1.55 (3H, s, gem CH3).

Methoxymethyl GP-hydroxypenicillanate (0.46 g) was dissolved in pyridine (2 ml) and pnitrobenzenesulphonylchloride (0.4 g) added. The solution was allowed to stand at 4"C for 24 hr., then poured onto iced water and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was separated, washed with dilute sulphuric acid (2 X 40 ml) and dried over an hydros sodium sulphate-sodium carbonate.Removal of the solvent in vacuo yielded methoxymethyl 6ss-(p-nitrobenzenesulphonyloxy)penicillanate (0.7 g) as a pale brown oil, vmax (CHCl3) 1800, 1750, 1540, 1350, 1190 cm-l; 8 (CDCl3) 8.43 (2H, d, J= 9Hz, ArH), 8.13 (2H, d, J= 9 Hz, Are, 5,78 (1H, d, J= 4 Hz, H-C5), 5.53 (1H, d, J= 4 Hz, H-C5), 5.28 (2H, s, CH2O), 4.45 (1 H, s, H-C3), 3.45 (3H, s, OCH3), 1.60 (3H, s, gem CH3), 1.50 (3H, s, gem CH3).

To a solution of methoxymethyl 6ss(p-nitrobenzenesulphonyloxy)penicillanate (0.1 8 g) in dimethylformamide was added lithium bromide (0.3 g). The solution was stirred overnight, then poured onto iced water and extracted with ethyl acetate (3 X 30 ml). The ethyl acetate layer was separated, washed with water and dried over anhydrous magnesium sulphate. The solution was then reduced to a small volume (5 ml), water (5 ml) was added and the pH was adjusted to 7.5 with sodium hydroxide.The aqueous layer was separated and the water removed in vacuo to yield a pale yellow glass (0.1 3 g) which on silica gel chromatography using butanol : ethanol water (4:1:1) as eluant yielded sodium 6ss-(p-nitrobenzenesulphonyloxy)penicillanate (0.07 g) as a pale yellow glass, y,,, (KBr) 1780, 1605, 1535, 1350, 1190 cm-'; 8 (D20) 8.34 (2H, d, J= 9 Hz, ArH), 8.05 (2H, d, J= 9 Hz, Are, 5.88 (1 H, d, J= 4 Hz, H-C5), 5.43 (1 H, d, J=4Hz, H-C5), 4.16 (1H, s, H-C3), 1.43 (3H, s, gem CH3), 1.35 (3H, s, gem CH3).

Example 9 Composition (a) A solution for injection may be prepared by dissolving 100 mg of sterile sodium 6ss- methane-sulphonyloxypenicillanate and 250 mg of sterile sodium amoxycillin in 1 ml of sterile water.

(b) A solution for injection may be prepared by dissolving 1 25 mg of sterile sodium 6ss- methanesulphonyloxypenicillanate and 1 25 mg of sterile cephaloridine in 1.5 ml of sterile water.

Demonstration 1 Sodium 6fi-methanesulphonyloxypenicillanate Benzyl 6ss-hydroxypenicillanate (0.202 g) was dissolved in chloroform (4 ml) containing dimethylformamide (0.1 5 ml). To this stirred solution at 0 C, was added methanesulphonyl chloride (0.052 ml) and triethylamine (0.092 ml). The reaction mixture was allowed to warm to room temperature. After 20 hours, the reaction mixture was diluted with chloroform (20 ml), washed with dilute sodium bicarbonate (20 ml), washed with water (20 ml), dried (MgSO4), and evaporated in vacuo to afford an oil. This oil was subjected to column chromatography on silica gel (25 g) using ethyl acetate:cyclohexane (1:3).The appropriate fractions were combined and evaporated in vacuo to afford benzyl GP-methanesulphonyloxypenicillanate as an oil (0.11 g); i.r. (liq film) 1795, 1740 cm-l; n.m.r. (CDCl3) 1.41 (3H, s), 1.64 (3H, s), 3.18 (3H, s), 4.51 (1H, s), 5.19 (2H, s), 5.57 (1H, d J=4Hz), 5.76 (1H, d J=4 Hz), 7.36 (5H, s).

Benzyl 6fl-methanesulphonyloxypenicillanate (0.1 0 g) was dissolved in a solvent mixture of tetrahydrofuran (3 ml), methanol (3 ml), and water (3 ml), and was hydrogenated over 5% Palladium on calcium carbonate (0.25 g) for 3 hours. The catalyst was filtered off and washed liberally with water and methanol. The combined filtrates were concentrated in vacuo to approximately 20 ml, and passed through an Amberlite IR-120 (Na6) ) ion-exchange column.

The eluent was co-evaporated with n-propanol to afford the title compound as a white solid (0.065 g), i.r. (KBr) 3400 (broad), 1785, 1740 sh, 1650 sh, 1605 cm-'; n.m.r. (D20) 1.48 (3H, s), 1.57 (3H, s), 3.30 (3H, s), 4.29 (1 H, s), 5.52 (1 H, d J= 4Hz), 5.98 (1 H, d J= 4Hz).

Demonstration 2 Sodium 6fi-methanesulphonyloxypenicillanate To a solution of benzyl GP-hydroxypenicillanate (1.8 g) in dichloromethane (10 ml) containing triethylamine (1.5 ml) at - 10" was added methanesulphonyl chloride (1.0 ml). The solution was stirred at 10 C for 1 5 min, then washed with iced water, dilute hydrochloric acid, sodium bicarbonate, brine and finally dried over anhydrous magnesium sulphate. Removal of the solvent in vacuo yielded benzyl 6fl-methanesulphonyloxypenicillanate as a pale yellow oil (2.1 g).

Benzyl 6ss-methanesulphonyloxypenicillanate (2.0 g) was dissolved in tetrahydrofuran (50 ml) containing water (3 drops) and 10% palladium-carbon catalyst (4 g). The mixture was hydrogenolysed at atmospheric pressure for + hr then filtered (celite) and the solvent evaporated in vacuo. The resulting oil was partitioned between ethyl acetate: water and neutralised with sodium hydroxide (0.5 M). The aqueous layer was separated and freeze dried to afford sodium 6ss-methanesulphonyloxypenicillanate as an off-white solid (1.2 g).

Demonstration 3 Sodium 6ss-phenylmethanesulphonyloxypenicillanate To a solution of benzyl 6ss-hydroxypenicillanate (0.5 g) in dichloromethane (10 ml) containing triethylamine (0.4 ml) at 10 C was added phenylmethanesulphonyl chloride (0.3 g). The solution was stirred at - 10"C for 15 min., then washed with iced water, dilute hydrochloric acid, sodium bicarbonate, brine and finally dried over anhydrous magnesium sulphate.Removal of the solvent in vacuo yielded benzyl 6ss-phenylmethanesulphonyloxypenicillanate as a pale yellow oil (0.61 g), may (CHCl3), 1790, 1740, 1380, 1190, 890 and 840cm-1; cm (CDCl3) 7.41 (10H, m, Ar H), 5.52 (1H, d, J=4Hz, H-C5), 5.37 (1H, d, J=4Hz, H-C5), 5.18 (2H, s, Ph-CH3-S), 4.53 (3H, s, Ph-CH3-O, and H-C3), 1.60 (3H, s, gem CH3), 1.43 (3H, s, gem CH3).

Benzyl 6ss-phenylmethanesulphonyloxypenicillanate (0.4 g) was dissolved in tetrahydrofuran (25 ml) containing 10% palladium-carbon catalyst (0.8 g) and water (3 drops). The mixture was hydrogenolysed at atmospheric pressure, for + hr. then filtered (celite) and the solvent evaporated in vacuo. The resulting oil was partitioned between ethyl acetate : water and neutralised with sodium hydoxide (0.5 M).The aqueous layer was separated and the water removed in vacuo to yield sodium 6-phenylmethanesulphonyloxy-penicillanate as a white solid (0.3 g), may (KBr) 1775, 1350, 1200, 1175, 890 and 840cm-1; 5 (D20) 7.49 (5H, s, Ar, 5.75 (1H, d, J= 4Hz, H-C5), 5.45 H, d, J= 4Hz, H-C5), 4.82 (2H, s, CH2-Ph), 4.25 H, s, H-C3), 1.55 (3H, s, gem CH3), 1.45 (3H, s, gem CH3), 12DO= + 167.8 (c 1.1 H20).

Demonstration 4 Sodium 6ss-benzenesulphonyloxypenicillanate To a solution of benzyl 6ss-hydroxypenicillanate (1.0 g) in pyridine (20 ml) was added benzenesulphonyl chloride (0.5 ml). The solution was allowed to stand at 4"C for 24 hr then poured on to iced water and extracted with ethyl acetate (2 X 40 ml). The ethyl acetate layer was then washed with dilute sulphuric acid (2 X 40 ml) and dried over anhydrous sodium sulphate-sodium carbonate.Removal of the solvent in vacuo yielded benzyl 6fl-benzenesulpho- nyloxypenicillanate as a pale yellow oil (1.04 g), ltmaX (CHCl3) 1790, 1740, 1190 cm-'; 8 (CDCl3) 7.83 (5H, m, ArH), 7.35 (5H, s, ArH ester), 5.65 (1 H, d, J = 3.5 Hz, H-C5), 5.45 (1 H, d, J= 3.5 Hz, H-C5), 5.18 (2H, s, CH2-Ph), 4.47 (1H, s, H-C3), 1.56 (3H, s, gem CH3), 1.38 (3H, s, gem CH3).

Benzyl 6ss-benzenesulphonyloxypenicillanate (1.1 g) was dissolved in aqueous tetrahydrofuran (10%, 30 ml), containing 10% palladium-carbon catalyst (2.3 g). The mixture was hydrogenolysed for < hr at atmospheric pressure then filtered (celite) and the solvent removed in vacuo to yield 6ss-benzenesulphonyloxy-penicillanic acid (0.8 g) as a pale yellow oil.The oil was dissolved in ethyl acetate (5 ml) and 2M sodium 2-ethyl hexanoate in methyl isobutyl ketone (1 ml) was added. 6ssbenzenesulphonyloxypenicillanic acid was precipitated as the sodium salt (on the addition of diethyl ether (50 ml)) in the form of a red brown solid which crystallised on addition of water as colourless needles, v (KBr), 1790, 1600, 1190 and 855 cm-; 8 (d5-DMSO) 7.85 (5H, m, ArH), 5.97 (1H, d, J= 3.5 Hz, H-C6), 5.33 (1H, d, J= 3.5 Hz, H-C5), 4.18 (1 H, s, H-C3), 1.45 (3H, s, gem CH3), 1.40 (3H, s, gem CH3), (a12D0 = + 157.3 (c. 0.67 H20).

Demonstration 5 Sodium 6fi-(p-aminobenzenesulphonyloxy)peniclllanate To a solution of benzyl 6ss-hydroxypenicillanate (0.5 g) in pyridine (10 ml) was added pnitrobenzenesulphonyl chloride (0.6 g). The solution was allowed to stand for 24 hr. at 4 C, then poured onto iced water and extracted with ethyl acetate (2 X 20 ml). The ethyl acetate layer was washed with dilute sulphuric acid (2 X 40 ml) and dried over anhydrous sodium sulphate-sodium carbonate.Removal of the solvent yielded benzyl 6ss-(p-nitrobenzenesulphony- loxy)-penicillanate as a pale yellow solid (0.5 g), Vmax (CHCl3) 1800, 1740, 1600, 1530, 1190 cm-' 8 (CDCl3) 8.40 (2H, d, J= 9 Hz, ArH), 8.13 (2H, d, J= 9 Hz, ArH), 7.35 (5H, s, CH2-Ph), 5.75 (1H, d, J=4 Hz, H-C6), 5.52 (1H, d, J=4 Hz, H-C5), 5.16 (2H, s, CH2-Ph), 4.47 (1 H, s, H-C3), 1.53 (3H, s, gem CH3), 1.36 (3H, s, gem CH3).

Benzyl 6ss-(p-nitrobenzenesulphonyloxy)penicillanate (0.37) was dissolved in aqueous tetrahydrofuran (20 ml) containing 10% palladium-carbon catalyst (0.7 g). The mixture was hydrogenolysed at atmospheric pressure, until hydrogen uptake ceased, then filtered (celite) and removed in vacuo. The resulting oil was partitioned between ethyl acetate : water and neutralized with sodium hydroxide (0.5M). The aqueous layer was separated and the water removed in vacuo to yield a pale yellow-glass which after silica gel chromatography (butanol:ethanol:water) (4:1:1) yielded sodium 6ss-aminobenzenesulphonyloxy)penicillanate as an off-white solid (0.1 g), #max (KBr) 1775, 1660, 1595, 1500, 1200, 1170 cm-; 8 (D30) 7.63 (2H, d, J= 9 Hz, ArH), 6.76 (2H, d, J= 9 Hz, ArH), 5.74 (1 H, d, J= 4 Hz, H-C6), 5.32 (1 H, d, J= 4 Hz, H-C5), 4.15 (1H, s, H-C3), 1.47 (3H, s, gem CH3), 1.35 (3H, s, gem CH3).

Demonstration of effectiveness In standard MIC tests the activities of the compounds of Example 1 and Demonstration 1 alone, and in combination with ampicillin were determined against Staph Russell and Proteus C889.

MIC Staph Proteus Russell C889 Ampicillin + Sodium 6ss- methanesulphonyloxypenicillanate & ommat; 20 gm- - 4 " " " " # 5, gml- inhib 125 " " " " # 1 gml- 0.08 - Ampicillin alone 62.5 1000 Sodium 6,B-methanesulphonyloxy- penicillanate alone 4 62.5 MIC Staph Proteus Russell C889 Ampicillin + Calcium 6-p-brnmobenzenesulphony- loxypenicillanate & ommat; 20, gml- inhib 16* " " " "# 5 gml- 0.16 - " " " " # 1 gml- 0.31 - Ampicillin alone 250 > 2000 Calcium 6-p-brnmobenzene- sulphonyloxypenicillanate alone 16 > 500 * trailing end-point A composition of sodium 6ss-methanesulphonyloxypenicillanate and cephaloridine against 7 cephalosporinase-producing E. coli strains results in the following MIC's in a standard test.

Geometric Mean + / - 95% confidence (MIC) limits Cephaloridine alone 152.38 (294.62-78.81) Cephaloridine + synergist 5 yg/ml) 11.32 ( 14.71- 8.71) Cephaloridine + synergist (20 yg/ml) 4.36 ( 9.12- 2.08)

Claims (10)

1. A pharmaceutical composition comprising: (a) a pharmaceutically acceptable carrier; (b) a compound of the formula (I):

and pharmaceutically acceptably salts and in vivo hydrolysable esters thereof, wherein n is O or 2, R1 is a C15 alkyl group optionally substituted with one, two or three fluorine, chlorine or bromine atoms, or is a di-C1 6 alkylamino group or is a group of the formula (i):

wherein X is a bond or a -CH = CH-group, or a methylene or ethylene group; R2 is a hydrogen, fluorine, bromine or chlorine atom, or is an amino, protected amino, hydroxy, protected hydroxy, C15 alkyl, nitro, di-C1 6 alkylamino, acetamido, C15 alkoxy or trifluoromethyl group;R3 is a hydrogen or chlorine atom or a C15 alkyl or trifluoromethyl group; and R4 is a hydrogen or chlorine atom, or a C15 alkyl or C15 alkoxy group; or R2 and R3 on any two adjacent carbon atoms may together represent a buta-1,3-dienylene moiety which is optionally substituted by a C13 alkyl or C13 alkoxy group; and (c) a penicillin or cephalosporin or a pharmaceutically acceptable salt or in vivo hydrolysable ester thereof.

2. A composition as claimed in claim 1 wherein n is zero.

3. A composition as claimed in claim 2 wherein R' is a methyl or ethyl group.

4. A composition as claimed in claim 2 wherein R' is a group of the formula (iii):

Wherein R2, R3 and R4 are as defined in relation to formula (I).

5. A composition as claimed in claim 4 wherein R3 and R4 are both hydrogen atoms and R2 is selected from hydrogen, bromine, fluorine, chlorine, C1-6 alkyl, nitro and amino.

6. A composition as claimed in any of claims 1-5 wherein the compound of the formula (I) is in the form of a sodium, potassium or calcium salt.

7. A composition as claimed in any of claims 1-6 wherein the penicillin is amoxycillin.

8. A composition as claimed in any of claims 1-6 wherein the cephalosporin is cephaloridine.

9. A compound of the formula (I) as depicted in claim 1, or pharmaceutically acceptable salt or in vivo hydrolysable ester thereof with the proviso that when n is zero, R' is not methyl, benzyl, p-chlorobenzyl, phenyl or p-aminophenyl when the compounds depicted in claim 1 are in the form of a free acid or a pharmaceutically acceptable salt.

10. A process for the preparation of a compound as claimed in claim 9 or salt or ester thereof which process comprises the reaction of a compound of the formula (III), or a derivative thereof which allows sulphonation to take place:

wherein n is zero and Ra is a hydrogen atom or a carboxy protecting group, with an 0sulphonating derivative of a compound of the formula (lV): R'SO3H (BV) wherein R' is as defined in claim 9; and thereafter if desired, (a) cleaving the carboxy protecting group to form the free acid or salt thereof.

(b) converting the free acid or salt into a pharmaceutically acceptable salt or in vivo hydrolysable ester.

(c) converting the compound wherein n is zero to the compound wherein n is 2.