GB1594934A - Clavulanic acid derivatives - Google Patents

Description

(54) CLAVULANIC ACID DERIVATIVES (71) We, GLAXO LABORA TORIES LIMITED, a British company of Greenford, Middlesex, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to novel antibiotics and to a process for their production.

In German OLS No. 2,604,697 we have described the isolation, from fermentations of Streptomyces clavuligerus, of clavulanic acid and salts thereof in pure form.

The compounds in this specification are named with reference to "clavam"; the name given to the parent heterocycle of formula A

by analogy with the term "cepham" used in the naming of cephalosporin compounds in J. Amer. Chem. Soc., 1962, 84, 3400. Thus, clavulanic acid is named (3R,5R,Z)- 2 (2 - hydroxyethylidene) clavam - 3 carboxylic acid.

Our copending British Application No.

23268/76 (Serial No. 1585124) relates to analogues of clavulanic acid and its salts and esters which carry an azido group -N3 or an amino group -NH2 in place of the hydroxy group thereof. These are of use as antibiotics or as A - lactamase inhibitors.

The present invention relates to the N acyl derivatives of the above amines which are also of use as antibiotics or ,B lactamase inhibitors.

Accordingly, we provide compounds of the formula

(where R is mono-acylamino group or a cyclic diacylamino group, the acyl groups of which are linked to form with the nitrogen atom a heterocyclic ring, and Rl is a carboxyl or esterified carboxyl group) and salt forms thereof.

The acylamino group R may be derived from a carboxylic or thiocarboxylic acid or a sulphonic acid; R may thus in general be represented by the grouping NR2R3 where R is a group -CYR4, -CY ZR6 or CYNR4RS, where Y and Z, which may be the same or different, are oxygen or sulphur; or -SO2NR4R' or -SO2R6, in which R4 and R5, which may be the same or different, are hydrogen or aliphatic, araliphatic, cycloaliphatic, aryl or Cattached heterocyclic groups or R5 together with R4 and the nitrogen atom to which they are attached form a heterocyclic ring, and R6 is a group as defined for R4 other than hydrogen; and R3 is hydrogen, or R2 and R3 together with the nitrogen atom to which they are attached form a heterocyclic group wherein the nitrogen is linked a di-acyl group, e.g. containing two carbonyl groups.

R may also be represented by the groupings -NH. CO CONR4RS or H CO COR4, where R4 and R5 are as defined above.

In general, it is preferred that R is a monoacylamino group, i.e. in the group -NR2R3, R3 is a hydrogen atom.

The groups R4, R5 and R6 may each be an alkyl or alkenyl group containing not more than 8 carbon atoms and each may, for example, be a straight or branched unsubstituted or substituted alkyl or alkenyl group, preferably having from 1--4 carbon atoms, for example, a methyl, ethyl, propyl or isopropyl, butyl, sec-butyl, tert-butyl or allyl group, optional substituents being for example, selected from one or more of alkoxy, e.g. methoxy; aryloxy, e.g. phenoxy; halogen, e.g. fluorine, chlorine or bromine; cyano; acyloxy, e.g. alkanoyloxy, such as acetoxy; acyl, e.g. acetyl; carboxyl; substituted carboxyl, for example alkoxycarbonyl, e.g. ethoxycarbonyl; azido; amino; substituted amino; hydroxyl or protected hydroxyl; thiol or substituted thiol; and cycloalkenadienyl, e.g. cyclohexadienyl. The term "substituted" as used herein in relation to carboxyl, amino, and thiol groups includes protected groups, i.e. groups which can readily be cleaved.

Suitable substituents on amino and thiol groups are alkyl, aralkyl and acyl groups.

The groups R4, RS and R6 may each be an aralkyl group having up to 10 carbon atoms, especially an arylmethyl group, e.g. a b enzl or substituted benzyl group. Suitable substituents on the phenyl ring of a benzyl group are hydroxy, e.g. p-hydroxy, or sulphonamido, e.g. m-sulphonamido.

Suitable substituents on the methylene group of a benzyl group include azido, amino, carboxyl or hydroxyl and protected forms thereof. Other aralkyl groups include heterocyclic aralkyl group, e.g. fur - 2 ylmethyl, thien - 2 - ylmethyl or pyrid - 4 ylmethyl groups, the heterocyclic groups of which may also be substituted, e.g. by a C1-4 alkyl group, preferably methyl.

The groups R4, R5 and R6 may each be an aryl group having up to 10 carbon atoms, e.g. a phenyl or substituted phenyl group, suitable substituents being halogen, e.g. chlorine; cyano; alkoxy, e.g. methoxy or alkyl, e.g. methyl The groups R4,'R5 and R6 may each be a cycloalkyl group containing not more than 10 carbon atoms, e.g. adamantyl, cyclopentyl or cyclohexyl.

The groups R4, RS and R6 may each be a C-attached 5-7 membered heterocyclic group, which may be saturated or unsaturated and may contain one or more heteroatoms selected from nitrogen, oxygen and sulphur, such as furyl, thienyl or pyridyl groups.

When NR2R3 form a ring this may, for example, have 5-7 ring members, preferably 5 as in the maleimido group; the ring may be fused to a further ring, e.g. a phenyl ring, as in the phthalimido group.

When R4 and R5 together with the nitrogen atom to which they are attached, form a heterocyclic ring, this desirably contains 5-7 ring members and may contain additional heteroatoms such as nitrogen, oxygen or sulphur atoms and may be substituted, for example, by an alkyl group, e.g. methyl.

Where R2 is a group -CYR4, Y is a sulphur atom or more preferably an oxygen atom and R4 is preferably a hydrogen atom; a C14 alkyl group; a C14 alkyl group substituted by 1-3 halogen atoms (e.g. fluorine, chlorine or bromine atoms), or a cyano, azido, hydroxyl, C14 alkoxy (e.g. methoxy or ethoxy), C,, alkanoyloxy (e.g. acetoxy) C1-4 alkylthio (which may be substituted by 1-3 halogen atoms), phenoxy, amino, C14 alkanoylamino, protected amino (e.g. benzyloxycarbonylamino), a carboxyl or protected carboxyl (e.g. a 4 methoxybenzyloxycarbonyl) group; a C,, alkenyl group; a benzyl group; a benzyl group substituted in the a-position by an azido, carboxyl, protected carboxyl (e.g. benzyloxycarbonyl), hydroxyl,. protected hydroxyl (e.g. formyloxy), amino or protected amino (e.g. benzyloxycarbonylamino) group and/or substituted in the phenyl ring by a hydroxyl group; a phenyl or pyridyl group; or a methyl group substituted by a carbonattached 5-7 membered heterocyclic ring in which the heteroatoms are selected from nitrogen, oxygen and sulphur atoms, especially when the heterocyclic ring is aromatic.

Where R2 is a group -CY. ZR6, Y and Z are preferably oxygen atoms and R6 is preferably a C1-4 alkyl group ar a benzyl group.

Where R2 is a group -CYNR4R5, Y is oxygen or sulphur and one of R4 and R5 is preferably a hydrogen atom, the other preferably being a hydrogen atom or a C14 alkyl group, a phenyl group or a carbonattached, saturated or unsaturated, 5-7 membered heterocyclic ring in which the heteroatoms are selected from oxygen, nitrogen and sulphur atoms.

Where RZ is a group -SO2R6, R6 is preferably a C14 alkyl group or a phenyl group or a phenyl group substituted by a methyl group.

Where R2 is a group -SO2NR4R3, R4 and R5, which may be the same or different, are preferably hydrogen atoms or C14 alkyl groups.

Thus representative groups R include formamido, acetamido, bromoacetamido, chloroacetamido, dichloroacetamido, trifluoroacetamido, trichloroacetamido, cyanoacetamido, azidoacetamido, acetoxyacetamido, hydroxyacetamido, methoxyacetamido, (methylthioacetamido, (trifluoromethylthio) - acetamido, phenoxyacetamido, aminoacetamido, benzyloxycarbonylaminoacetamido, (N, formylamino)acetamido, (N acetylamino)acetamido, propionylamino, 3 - (4 - methoxybenzyloxycarbonyl) propionylamino, 3-carboxypropionylamino, acryloylamino, butyrylamino, isobutyrylamido, 3 - ethoxypropionyl amino, phenylacetamido, 2 - azido - 2 phenylacetamido, 2 - amino - 2 phenylacetamido, 2 - hydroxy - 2 phenylacetamido, 2 - formyloxy - 2 phenylacetamido, 2 - (benzyloxycarbonyl) - 2 phenylacetamido, 2 - carboxy - 2 phenylacetamido, 2 - (benzyloxy carbonylamino) - 2 - phenylacetamido, (4 - hydroxyphenyl)- acetamido, thien 2 - ylacetamido, thien - 3 - ylacetamido, fur - 2 - ylacetamido, pyrid - 4 ylacetamido, benzamido, pyrid - 2 ylcarbonylamino, pyrid - 3 ylcarbonylamino pyrid - 4 - ylcarbonylamino, succinimido, maleimido, phthalimido, oxamido, phenylglyoxamido, methoxycarbonylamino, ethoxycarbonyl. amino, thiobenzamido, ureido, methylureido, ethylureido, phenylureido, thien 2 - ylureido, pyrid - 3 - ylureido, thioureido, methylthioureido, phenylthioureido, (tetrahydropyran - 2 yl)ureido, methylsulphonamido, p-tolylsulphonamido, phenylsulphonamido, dimethylsulphamoylamino and methyl sulphanoylamino groups.

It will be appreciated that when the group R contains a chirnal centre as in a 2,2 disubstituted acetamido group, such groups may be in the "R-" or "S" form, or the compound of formula (I) may comprise a mixture, e.g. a racemic mixture, of compounds having groups R in the "R-" and "S--" forms.

The esters according to the invention may in general be represented as compounds of formula I in which Rl is a group COOR7 where R7 represents an organic group which is conveniently derived from an alcohol (aliphatic or araliphatic), a phenol or a stannanol. Such as alcohol, phenol or stannanol used to esterify the carboxy group preferably contains not more than 24 carbon atoms.

Thus, the group R7 may represent a straight or branched unsubstituted or substituted alkyl or alkenyl group, preferably having from 1-8 carbon atoms, for example a methyl, ethyl, propyl, or isopropyl, butyl, sec-butyl, tert-butyl or allyl group, desirable substituents being, for example, alkoxy, e.g. methoxy; halogen, i.e. fluorine, chlorine, bromine, or iodine; cyano; acyloxy, e.g. alkanoyloxy, such as acetoxy, or pivaloyloxy; acyl e.g. p bromobenzoyl; and alkoxycarbonyl, e.g. ethoxycarbonyl; an aralkyl group having up to 20 carbon atoms especially an arylmethyl group, e.g. a benzyl or substituted benzyl group, suitable substituents being either halo, e.g. chloro; nitro, e.g. o- orp-nitro; cyano; alkoxy, e.g. methoxy, such as methoxy; or alkyl, e.g. methyl, such as p-methyl, groups; a diphenylmethyl or triphenylmethyl group or a fur - 2 - ylmethyl, thien - 2 - ylmethyl or pyrid - 4 - ylmethyl group, the heterocyclic groups of which may also be substituted, e.g. by a C,, alkyl group, preferably methyl; an aryl- group having up to 12 carbon atoms, e.g. a phenyl or substituted phenyl group, suitable substituents being either halo, e.g. chloro; nitro, e.g. o- or p-nitrol cyano; alkoxy, e.g. methoxy or alkyl e.g. p-methyl groups; a cycloalkyl group containing not more than 12 carbon atoms e.g. adamantyl; a heterocyclic group containing not more than 12 carbon atoms, the hetero atom being, for example, oxygen, as in the tetrahydropyranyl or phthalidyl group; or a stannyl group having up to 24 carbon atoms, for example a stannyl group carrying three substituents which may be the same or different selected from alkyl, alkenyl, aryl, aralkyl, cycloalkyl, alkoxy, or aralkoxy groups. Such groups will include methyl, ethyl, propyl n-butyl, phenyl and benzyl groups.

Where Rl represents a carboxyl group the compounds of formula (I) can form salts with bases. The salts with bases may-be salts with inorganic bases such as alkali metal salts, e.g. sodium, potassium and lithium salts; alkaline earth metal salts, e.g. calcium and magnesium salts and ammonium salts; or salts with organic bases, for example amine salts.

Where the group R contains a basic group, e.g. an amino group, the compound of formula (I) may form acid addition salts, e.g. with inorganic or organic acids, for example, hydrochlorides, sulphates, p - toluene - sulphonates or trifluoroacetates.

Where Rl is a carboxy group and R contains a basic group the compounds of formula (I) may exist in zwitterionic from.

The compounds of the invention generally exhibit p-lactamase inhibitory activity, and are of use in the protection of p-lactam antibiotics susceptible to A- lactamase hydrolysis.

The free acids of the invention and their salts and metabolically labile esters in general show antibiotic activity. Where the carboxylate ester is metablically labile, the parent acid will be generated in vivo.

Examples of such esters include the acyloxymethyl esters, e.g. the alkanoyloxymethyl esters such as acetoxy methyl and pivaloyloxymethyl esters, and the cr-alkoxycarbonyloxyalkyl esters such as I - ethoxycarbonyloxyethyl esters.

Where the carboxylic ester grouping is readily cleaved, e.g. by hydrolysis or reduction, without significant degradation of the remainder of the molecule, the esters are especially useful as carboxyl protected derivatives of the parent acids. Certain esters may be of use either in the purification or characterisation of the acids according to the invention or as carboxyl protected intermediates for use in preparing further derivatives.

Esters which serve particularly well as carboxyl-protected intermediates and which are primarily of use in this connection include the arylmethyl esters as detailed above, especially the benzyl, p--nitrobenzyl, - benzhydryl and trityl esters, as well as stannyl, e.g. tri-n-butyl-stannyl esters.

The compounds of the invention for which we have demonstrated antibiotic activity have been active against a range of gram-negative and gram-positive micro organisms, for example, against strains of Staphylococcus aureus, Esterichia coil, Salmonella typhimurium, Shigella sonnet, Enterobacter cloacae, Klebsiella aerogenes, Proteus mirabilis, Proteus vulgaris, Proteus organ it and Haemophilus influenzae.

In general, the compounds are stable to the action of p-lactamases produced by gram-positive organisms, for example those produced by Staphylococcus aureus, and to the p-lactamases produced by gram negative organisms.

As stated above the compounds generally have the ability to inhibit P - lactamase enzymes; these include enzymes produced by gram-positive organisms, for example those produced by strains of Staphylococcus aureus and also enzymes from gram negative bacteria produced, for example, by strains of Proteus mirabilis, Escherichia coli, Klebsiella aerogenes, Salmonella typhimurium, Haemophilus influenzae, Bacteroides fragilis, Proteus vulgaris, Proteus rettgeri, and Neisseria gonorrhoeae.

Certain compounds of the invention, including compounds of formula (I) wherein R' represents a carboxyl group, optionally in salt form and R is an acetamido, formamido, benzamido, phenylureido, toluenesulphonamido, ethoxy carbonylamino, ethylureido or methoxy carbonylamino group are also absorbed when administered orally as shown by studies in mice.

The new antibiotic acids and their physiologically acceptable salts and metabolically labile esters are of interest for use in conjunction with both injectible and orally absorbed B - lactam antibiotics which show susceptibility to B - lactamases from both gram-positive and gram-negative organisms.

In general, it is preferred to use the active compounds of the invention in conjunction with a broad spectrum p-lactam antibiotic, which may be of a type conventionally administered by the oral or parenteral route. Use of the antibiotic acids and their salts is especially preferred.

Examples of orally absorbed broad spectrum p-lactam antibiotics include cephalexin, cephaloglycin, ampicillin and amoxycillin and their orally absorbed esters, e.g. the acyloxymethyl and phthalidyl esters, and the orally absorbed esters of carbenicillin, ticarcillin and mecillinam, e.g. the indanyl, phenyl and pivaloyloxymethyl esters. Broad spectrum p-lactam antibiotics which are not orally absorbed include carbenicillin, ticarcillin, mecillinam, cephalothin, cephaloridine, cefazolin, cephacetrile and cephapirin. Examples of narrow spectrum p-lactam antibiotics are penicillin G and penicillin V.

The above antibiotics may also be in the form of their metabolically labile esters, pharmaceutically acceptable salts and/or solvates thereof.

Combinations of the active compounds of the invention with for example ampicillin and/or amoxycillin generally show synergistic activity against p-lactamase producing organisms including strains of, for example, Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes, Proteus mirabilis, Neisseria gonorrhoeae, Bacteroides fragilis, Proteus rettgeri and Proteus vulgaris.

Particularly preferred compounds of formula (I) are those in which R represents a formamido, acetamido or phenylureido group and R1 is a carboxyl group or a salt thereof; The active compounds of the invention may be of use, either alone or in combination with a further B-lactam antibiotic, in treating a variety of diseases of humans and animals caused by pathogenic bacteria, such as respiratory or urinary tract infections.

According to a further feature of the invention, we provide pharmaceutical compositions, (including veterinary compositions) containing at least one of the acids, physiologically acceptable salts or metabolically labile esters of the invention.

In view of the protective action described above, the compositions can advantageously contain further p-lactam antibiotics such penicillins and cephalosporins, orally absorbed p-lactam antibiotics being especially preferred when the compound according to the invention is also orally absorbed. The compositions will normally also contain a pharmaceutical (including veterinary) carrier or excipient.

The compositions of the invention include those in a form adapted for oral or parenteral use.

The compositions may, for example, take the form of powders, tablets, capsules, lozenges, solutions and syrups suitable for oral administration, and may include, for example, starch, lactose, talc, magnesium stearate, gelatin, distilled water and suspending, dispersing, emulsifying, flavouring or colouring agents.

The active compounds may further be formulated in rectal compositions such as suppositories or retention enemas.

The active compound of the invention may be formulated for parenteral administration e.g. for injection. The compounds may thus be formulated in ampoules for reconstitution before use, optionally together with a further antibiotic compound.

In general, the weight ratio of the compound of the invention to a further ,B- lactam antibiotic to be protected will be in the range 10:1 to 1:10, more preferably 5:1 to 1:5, especially 2:1 to 1:2.

The active compounds of the invention will generally be administered to adults at a total daily dosage level of 50 mg to 20 g, preferably from 100 mg to 10 g, which may be in divided doses given from 14 times per day. Where the composition. contains a further p-lactam antibiotic, the total quantity of B-lactam antibiotic will desirably be from 100 mg, to 20 g, which may be given in divided doses from 1--4 times a day. In general, the total daily dosage of plactam antibiotic when the active compound of the invention is used either alone or in combination with a further plactam antibiotic will advantageously be from 250 mg to 5 g. Dosage units will in general contain 12.5 mg to 5 g, preferably 50 mg to 1 g, of active compound according to the invention when used alone and 25 mg to 5 g, preferably 100 mg to 1 g, of total B-lactam antibiotic where a further antibiotic is present.

According to a further feature of the invention, we provide a process for the preparation of a compound of formula I as defined above which comprises reacting the parent amino acid (R=NH2; R'=COOH) or a salt or ester thereof with an acylating agent.

In general, the acylating agent may be of the formula R2X where R2 has the above meaning and X is a displaceable substituent.

The substituent X may, for example, be a halogen atom, e.g. chlorine or bromine, an O-acyl group, an O-hydrocarbyl group or a hydroxyl group. Thus for example, R2X may be a carboxylic or thiocarboxylic acyl halide, carbamoyl halide, thiocarbamoyl halide, sulphamoyl halide, sulphonyl halide or haloformyl ester (X=halogen); a carboxylic or thiocarboxylic acyl anhydride, which may be symmetrical or mixed (X=O Acyl); a carboxylic, thiocarboxylic or sulphonic acid in the presence of a coupling agent such as dicyclohexylcarbodiiimide (X=OH); or an active ester of a carboxylic, thiocarboxylic or sulphonic acid. The acylating agent may, however, also be a ketene or sulphene or an isocyanate or isothiocyanate or an activated imide.

In order, to avoid complicating sidereactions, the acylation reaction may be carried out using an ester of the parent amino acid. The use of an ester is particularly preferred in reactions involving the use of a carboxylic, thiocarboxylic or sulphonic acid in the presence of a coupling agent such as dicyclohexylcarbodiimide. The ester will preferably be an arylmethyl ester, e.g. a benzyl ester.

In many cases, acylation of the parent amine acid or esters thereof may be assisted by the presence of a bis-trialkyl tin oxide, such as bis-tri-n-butyl tin oxide.

Activated imides will generally be N-acyl cyclic imides. and these have been found useful acylating agents. Such compounds will generally have the formula R2R3N CY. R8 wherein R2 and R3 together with the nitrogen atom to which they are attached, form a heterocyclic ring, in which the nitrogen is linked to two carbonyl groups, Y represents oxygen or sulphur and R8 represents R4 or ZR6 where R4, R6 and Z are as defined above. However, the orientation of nucleophilic attack has been found dependent upon the relative susceptibility to attack of the carbon or thiocarbonyl group(s) in the imide. Thus, as will be seen from the Examples, reaction of the parent amine acid (R=NH2, R'=COOH) with N - ethoxycarbonylsuccinimide yields the N - ethoxycarbonylamino compound of the invention and reaction of the same amine acid with N - thiobenzoylsuccinimide gives the thiobenzamido compound of the invention. On the other hand reaction of the amine acid with N ethoxycarbonyl - phthalimide gave the compound of formula (I) in which R is a phthalimido group. In general, succinimides are preferred for formation of monoamides.

In some cases it may be preferable to form an activated derivative of the parent amine prior to acylation, e.g. a C13 trialkylsilyl derivative such as trimethylsilyl derivative. Carboxylic acyl, thiocarboxylic acyl, sulphonyl, carbamoyl or sulphamoyl halide reagents are preferably the chlorides.

Mixed anhydride reagents preferably contain the acyl group to be introduced attached to a tertiary alkanoyloxy or C15 alkoxycarbonyloxy grouping, e.g. pivaloyloxy or ethoxycarbonyloxy. Reactive ester reagents include aryl esters, especially aryl esters carrying electron withdrawing substituents, e.g. nitrophenyl esters.

Reactive ester reagents prepared from N hydroxyimides, e.g. N - hydroxysuccinimide, and from other reagents, e.g.

1 - hydroxybenzotriazole or 2 mercaptopyridine, may also be used. The reactive ester reagent may conveniently be formed in situ.

It may be convenient to carry out the reaction in the presence of a base, preferably a weak base, e.g. an inorganic base such as an alkali metal carbonate or bicarbonate or an organic base, e.g. a tertiary base such as a trialkylamine, particularly when the aminoacid (Zwitterion) form of the parent amine or an acid addition salt thereof is used as starting material or, where the acylating agent liberates acid, the base thereby functioning as an acid binding agent.

Suitable solvents for the reaction include aprotic solvents such as an amide, e.g. dimethylformamide, dimethylacetamide or hexamethylphosphoramide; an ester, e.g. ethyl acetate; an ether, e.g. tetrahydrofuran or dioxan; a ketone, e.g. acetone; a halogenated hydrocarbon, e.g. dichloromethane or chloroform; a substituted sulphoxide, e.g. dimethylsulphoxide; or mixtures of the above solvents. The parent amine (R=NH2; Rl=COOH) in Zwitterionic form is of relatively low solubility and when this compound is used as starting material in the reaction an aprotic, dipolar solvent such as dimethylformamide, dimethylacetamide or hexamethylphosphoramide is preferably used. Reactions with acyl halides and anhydrides may also be effected in aqueous solutions, e.g. aqueous acetone or tetrahydrofuran. The reaction is advantageously effected at or below room temperature e.g. in the range -20" to +350C.

Where an acid of formula (I) is formed initially and an ester is required, the acid or a reactive derivative thereof may be reacted with an alcohol, phenol or stannanol or a reactive derivative thereof. Reaction will desirably be effected under neutral conditions in order to prevent rupture of the bicyclic nucleus. The use of neutral or mild acidic or basic conditions, therefore, at temperatures between 70a and +35"C is preferred.

The alkyl, alkoxyalkyl and aralkyl esters may be prepared by reaction of the acid of formula (I) (Rl=COOH) with the appropriate diazoalkane or diazoaralkane, e.g. diazomethane or diphenyldiazomethane. The reaction will generally be effected in an ether, ester or a halohydrocarbon solvent, e.g. diethyl ether, ethyl acetate or dichloromethane. In general, reduced temperatures are preferred, for example 150 to +150C.

The esters derived from alcohols may be produced by reaction of a reactive derivative of the alcohol, for example, a halide such as chloride, bromide or iodide, or hydrocarbonsulphonyl derivative such as mesyl or tosyl ester, with a salt of the acid of formula (I), e.g. an alkali or alkaline earth metal salt such as a lithium, sodium, potassium, calcium or barium salt or an amine salt, such as a triethylammonium salt.

This reaction is preferably carried out in a substituted sulphoxide or amide solvent, e.g. dimethyl sulphoxide, dimethylformamide or hexamethylphosphoramide.

Stannyl esters may conveniently be formed by reaction of the carboxylic acid of formula I or a salt therof with reactive tetravalent tin moieties. Trialkyl tin oxides are preferred for the synthesis of tin compounds in view of their availability of low toxicity.

Where the initial product is an ester and a carboxylic acid or salt is required, the compound may be subjected to deesterification. Thus, for example, a stannyl ester can be cleaved by very mild solvolysis, e.g. by reaction with water, alcohols, phenols or carboxylic acids such as acetic acid.

Arylmethyl esters such as benzyl, benzyhydryl, trityl or p-nitrobenzyl esters can be cleaved by reduction, e.g. catalytic reduction using, for example a noble metal catalyst such as palladium. In t grouping, e.g. using the methods described above.

During reductive cleavage of an ester group, other atoms or groups may be reduced. Thus, for example, an acryloylamino group may be converted into a propionylamino group, an azidoacetamido group into an aminoacetamido group or a bromoacetamido group into an acetamido group. Similarly, when an acid of formula (I) or salt thereof contains a reducible atom or group, this may be subjected to reduction in a manner similar to that described above.

As indicated above, the group R may carry protected hydroxyl, thiol, amino or carboxyl groups and where free hydroxyl, thiol, amino or carboxyl groups are desired, the protected forms may be deprotected by conventional methods. Thus, for example, a benzyloxycarbonylamino substituent in the group R may be deprotected to yield an amino substituent by reduction, e.g. using methods described hereinabove for deesterification.

Where it is desired to produce a salt of the compound of formula (I), an acid initially formed in solution in an appropriate organic solvent may be reacted with an appropriate base, preferably under conditions favouring precipitation of the salt. In the formation of, for example, alkali metal salts, e.g. sodium or potassium salts, an alkanoate is a preferred base, e.g. a 2 ethyl - hexanoate.

The parent amines of formula I in which R is an amino group may be prepared from compounds of formula I in which R is an azido group by reduction, for example by catalytic hydrogenation; the catalyst is preferably palladium, e.g. as 10% palladium on charcoal, and a suitable solvent for the reduction of an acid or an ester is an ester such as ethyl acetate, an alcohol such as ethanol, or a mixture thereof. Such a solvent may advantageusly be admixed with water or an aqueous buffer. In some combinations a two phase system may result.

Certain esters used as starting material may be cleaved during hydrogenation, e.g. arylmethyl esters such as the benzyl or p nitrobenzyl esters, to yield the amine containing a free carboxyl group.

However certain arylmethyl ester groups are less susceptible to cleavage when reduction is effected using a dissolving metal and it is possible, for example, to selectively reduce the azido group of the benzyl ester by a dissolving metal reducing agent without cleaving the benzyl group.

Where the ester group is not cleaved during hydrogenation, the product may be isolated as the free amine or as a salt thereof.

The azido starting materials may be prepared by, for example, reaction of sodium azide with an ester of (3R5R,Z) 2 - (2 - chloroethylidene)clavam - 3 carboxylic acid, which compound may be obtained by processes as described in our German OLS 2657081.

The invention will now be further described in the following Preparations and Examples which should not be construed as limiting the invention.

The following Preparations illustrate the means whereby the starting materials for the preparation of the compounds of the invention may be obtained.

In the Examples which follow, ACC denotes (3R,5R,Z) - 2 - (2 aminoethylidene)clavam - 3 - carboxylic acid, BAC denotes benzyl (3R,5R,Z) - 2 (2 - aminoethylidene)clavam - 3 car6Oxylåte, and DCC denotes N,N dlcyclohexylcarbodimide.

For each of the new compounds prepared, only selected NMR values are given. All temperatures are in "C.

Preparation 1 4-Nitrobenzyl (3R,5R,Z)-2-(2-azido ethylidene)clavam-3-carboxylate A mixture of 4 - nitrobenzyl (3R,5R,Z) 2 - (2 - chloroethylidene)clavam - 3 carboxylate (0.5g), sodium azide (0.092 g), acetone (15 ml), water (1.5 ml) and acetic acid (ca. 1.0 ml) was stirred at ambient temperature for 15 minutes and then partitioned between ether and water. The organic phase was washed with water, dried (Na2SO4) and concentrated to ca. 10 ml. The residue was loaded onto a dry column of silica gel which was then eluted with ether.

Fractions were collected and combined on the basis of thin layer chromatographic examination and the solution concentrated.

On standing at 0 the solution deposited pale yellow crystals. The crystals were collected, washed with either and dried in vacuo to afford the title ester (0.078 g), m.p.

6364", []D+38O (c 0.9; EtOAc), P (CHBr3) 1796 cm-1 (p-lactam), T (CDCl3), 4.22 (d, J 2Hz, C-S H) and 6.10 (d, J 7Hz, CH2N,).

Preparation 2 (3 R,5 R,Z)-2-(2-aminoethylidene) clavam-3-carboxylic acid 4 - Nitrobenzyl (3R,5R,Z) - 2 - (2 azidoethylidene)clavam - 3 - carboxylate (0.2 g) was hydrogenated at atmospheric pressure and ambient temperature in a mixture of ethyl acetate (10 ml) and ethanol (10 ml) over 10% palladium on carbon (0.2 g) for 2 hours. The mixture was partitioned between ethyl acetate (20 ml) and water (50 ml) and the catalyst removed by filtration.

The aqueous phase was washed with ethyl acetate and lyophilised to afford the title acid as a buff powder (0.092 g), Vmax 1780 cm-' (p - lactam), T (D2O) 4.22 (d, J 2Hz, C-S H) and 6.30 (d, J 7Hz, 0 CH2NH3).

Preparation 3 Sodium (3 R,5 R,Z)-2-(2-azidoethyli dene)clavam-3-carboxylate Zinc dust (1.9 g) was added in small portions over a 2 hour period to a stirred solution of 4 - nitrobenzyl (3R,5R,Z) - 2 (2 - azidoethylidene)clavam - 3 carboxylate (1.5 g) in tetrahydrofuran (80 ml) and water (50 ml) which was maintained at 0 by cooling and at pH 4.3 by the dropwise addition of NHCl. The resulting mixture was stirred for a further 1 hours, filtered and partitioned between ethyl acetate (150 ml) and water (100 ml).

Hydrogen sulphide was passed through the two phase mixture and the pH of the aqueous phase maintained between 2.5 and 4.5 by the addition of N NaOH solution.

When the pH had become steady at 4.5, the mixture was filtered through kieselguhr and the separated organic layer extracted with 0.5N aqueous NaHCO3 solution (x3). These extracts were combined with the separated aqueous layer, washed with ethyl acetate, acidified to pH2 with 2N HCI and extracted with ethyl acetate. The organic extract was dried over magnesium sulphate, filtered and treated with a solution of sodium 2 ethylhexanoate (0.6 g) in ethyl acetate. The resulting solution was concentrated to ca, 2 ml and slowly diluted with ether. The precipitate was collected, washed with ether and dried to afford the title salt (0.45 g), [a]0+510 (e 0.95; H2O), Pmax(Nujol) (Nujol is a registered Trade Mark), 1782 cm-' CO - lactam), T (D2O) 4.19 (d, J 3Hz, C-5H), and 6.03 (d, J 9Hz, CH2N3).

Preparation 4 Methyl (3 R,5 R,Z)-2-(2-azidoethyl idene)clavam-3-carboxylate An aqueous solution of sodium (3R,5R,Z) - 2 - (2 - azidoethylidene)clavam - 3 - carboxylate (0.2 g) was acidified with 2N HCl and extracted with ethyl acetate. The organic solution was dried (MgSO4) and treated at 0 with an excess of ethereal diazomethane.

The solution was purged with a stream of nitrogen for 10 minutes and then evaporated dto give the title ester as in oil (0.16 g), [α]20+66 (c 0.85; CHCl3), #maxx (CHBr3), 1798 cm-1 (ss - lactam); #(CDCl3) 4.27 (d, J 3Hz, C-5H), and 6.13 (d, J 8Hz, -CH2N3).

Preparation 5 B enzyl (3R,5R,Z)-2-(2-azidoethyl idene)clavam-3-carboxylate A stirred solution of benzyl (3R,5R,Z) 2 - (2 - hydroxyethylidene)clavam - 3 carboxylate (1.0 g) in ether (20 ml) under nitrogen was cooled to -55 and trated with pyridine (0.8 ml) followed by thionyl bromide (0.34 ml) in ether (5 ml). The resulting mixture was stirred for 10 minutes at ca -45 and was then pured into water.

The organic phase eas washed with water and was then treated with a solution of sodium azide (0.26 g) in a mixture of water (3 ml) and acetone (20 ml). The resulting mixture was concentrated by evaporation until homogeneous treated with acetic acid (ca 0.2 ml) and stood at room temperature for 10 minutes. The solution was partitioned between ether and water and the organic layer was washed with water and brine. The dried solution was concentrated to ca 10 ml and chromatographed on a dry column of silica gel with ether as eluant. Appropriate fractions were combined and evaporated to an oil. The oil was redissolved in chloroform and evaporated to give the title ester as an oil (0.395 g), #max (CHBr3) 1792 cm-1 (ss lactam), # (CDCl3), 4.29 (d, J 3Hz, C-5 H), and 6.17 (d, J 8Hz, -CH2N2).

Preparation 6 Benzyl (3 R,5R,Z)-2-(2-aminoethyl- idene)clavam-3-carboxylate A stirred solution of benzyl (3R,5R,Z) 2 - (2 - azidoethylidene)clavam - 3 carboxylate (0.1 g) in tetrahydrofuran (2 ml) was treated with zinc dust (0.2 g) in small portions over a 5 minute period while the pH was maintained between 2 and 4 by dropwise addition of 2N HCI. The resulting mixture was decanted from the zinc residue and partitioned between brine and ethyl acetate. The aqueous phase at pH 5 was extracted with ethyl acetate. The organic extract was dried (Na2SO4) and evaporated to give a gum. The gum was redissolved in chloroform and evaporated to yield the title ester as a foam (0.092 g), #max (CHBr3), 1798 cm-1 (ss - lactam), # (CDCl3), 4.31 (d, J 2 Hz, C-5) and 6.41 (d, J 7Hz, -Ch2NH2).

Preparation 7 Methyl (3 R,5 R,Z)-2-(2-aminoethyl idene)clavam-3-carboxylate Zinc powder (1.2 g) was added in portions over a 20 minute period to a stirred solution of methyl (3R,5R,Z) - 2 - (2 azidoethylidene)clavam - 3 - carboxylate (0.5 g) in tetrahydrofuran (25 ml) and water (15 ml) which was maintained at 0 by cooling and at pH 4-4.5 by the dropwise addition of N HCI. The mixture was stirred for a further 20 minutes and was then filtered and partitioned between saturated brine at pH 7.2 and ethyl acetate. The separated aqueous phase was extracted with further ethyl acetate and the combined organic extracts were dried (MgSO4) and evaporated to yield the title ester as a gum, #max (CHBr3) 1790 cm-1 (ss - lactam; # (DMSO-d6) 4.17 (d, J 2Hz, C-5H), 4.68 (s, C-3 H), 6.21 (s, CH3) and 6.54 (m, CH2NH2).

Example 1 Sodium (3R,5R,Z)-2-(2-acetamido ethylidene)-clavam-3-carboxylate A solution of acetic anhydride (0.58 g) in acetone (5 ml) was added dropwise over 10 mins. to an ice-cold solution of ACC (0.90 g) and NaHCO3 (0.96 g) in 50% aqueous acetone (45 ml). After addition was complete, the mixture was stirred at room temperature for 30 min, then poured into saturated brine (50 ml). The solution was acidified with dilute aqueous HCl to between pH 3 and 4 and extracted with ethyl acetate (6x50 ml). The organic extracts were discarded and the aqueous phase acidified to pH 2. The acidic solution was further extracted with ethyl acetate (50 and 30 ml). The organic extracts were combined and dried (Na2SO4), then added to a solution of sodium 2 - ethylhexanoate (0.35 g) in ethyl acetate. The mixture was stirred for 15 min. at room temperature, then partially concentrated (to ca 30 ml) in vacuo and the mother liquors decanted from the deposited solid. The solid was collected, washed with ether and dried to yield title compound (190 mg) []D=38O (C 0.75, H2O), #max 1786 cm-' (ss - lactam), T (d2O) 4.30 (d, C-5H), 6.18 (d, C--2' protons) and 8.05 (s, -COCH3).

Example 2 Sodium (3R,5R,Z)-2-(2-phenylureido ethylidene)-clavam-3-carboxylate Phenyl isocyanate (0.48 ml) was added dropwise over 5 mins to a suspension of ACC (0.44 g) and triethylamine (0.46 ml) in dimethylformamide (6 ml). After stirring for a further 20 min at 200, the mixture was diluted with ethyl acetate (50 ml) and extracted with saturated aqueous NaHCO3 solution (3x25 ml). The aqueous extracts were combined, saturated with NaC1 and adjusted to pH 2 with dilute aqueous HCI.

The acidic solution was extracted with ethyl acetate (3x30 ml). The organic extracts were combined, washed with pH 2 buffer (4x25 ml) and dried (Na2SO4). A solution of sodium 2 - ethylhexanoate (0.23 g) in ethyl acetate (5 ml) was added to the extracts and the mixture concentrated to a small volume (ca 5 ml) in vacuo. The concentrate was cooled on an ice-bath and diluted with ether (25 ml). The deposited solid was filtered off, yielding title compound (350 mg), Pmax 1784 cm-' (p-lactam), T (D2O) 2.68 (phenyl protons), 4.27 (d,5-H). 6.15 (d, C--2' protons).

Example 3 Sodium (3R,5R,Z)-2-(2-benzamidoethyl idene)-clavam-3-carboxylate A solution of benzoic anhydride (0.28 g) in acetone (1.5 ml) was added dropwise over 10 min to a solution of ACC (0.20 g) and NaHCO3 (0.21 g) in 50% aqueous acetone (10 ml) cooled in an ice-bath. After addition was complete, the mixture was stirred for a further 30 min at room temperature then added to saturated brine (20 ml). The mixture was adjusted to pH 5.5 with dilute aqueous HCI and extracted repeatedly with ethyl acetate until removal of benzoic acid was complete. The aqueous phase was acidified to pH 2 with dilute aqueous HCI and extracted with ethyl acetate (2x25 ml).

The organic extracts were dried (Na2SO4) and added to a solution of sodium 2 ethylhexanoate (83 mg) in ethyl acetate (5 ml). The mixture was concentrated to a small volume in vacuo and then diluted with ether (20 ml). The precipitated solid was filtered off and dried, yielding the title compound (92 mg), T (D2O) 2.2-2.6 (phenyl protons), 4.28 (d, C-S H) and i.93 (d, C-2' protons). The title compound having spectral properties similar to those described above may also be prepared from ACC using benzoyl chloride.

Example 4 Sodium (3R,5R,Z)-2-(2-phenylthioureido- ethylidene)clavam-3-carboxylate Phenyl isothiocycanate (0.12 ml) was added to a suspension of ACC (0.10 g) in dimethylformamide (2 ml, containing 0.1 ml of triethylamine) and the mixture stirred at room temperature for 1 hr. The mixture was diluted with ethyl acetate (15 ml) and extracted with aqueous NaHCO3 solution (3 x 15 ml). The aqueous extracts were combined and washed with ethyl acetate (25 ml) and acidified to pH2 with dilute aqueous HCI. The acidic solution was saturated with NaCI and extracted with ethyl acetate (2x25 ml). The organic extracts were washed with brine (2x25 ml, buffered to pH2), dried (Na2SO4) and added to a solution of sodium 2 - ethylhexanoate (0.040 g) in ethyl acetate (2 ml). The solution was concentrated to ca. 2 ml in vacuo and ether (25 ml) added to the concentrate. The precipitated solid filtered off and dried in a desiccator to yield the title salt (0.072 g), Vmax (Nujol) 1784 cm-l (ss lactam), T (D2O) 2.5-2.8 (aromatic protons), 4.33 (d, J 2Hz, C--5H) and 5.8-5.9 (m, C-2' protons).

Example 5 Sodium (3R,5R,Z)-2-(2-tosylaminoethyl- idene)clavam-3-carboxylate A stirred solution of ACC (0.1 g) in 0.5 M aqueous NaHCO2 (2 ml) was treated with tosyl chloride (0.12 g) in acetone (2 ml). The mixture was stirred at ambient temperature for 15 min. and then the acetone removed by evaporation. The residue was partitioned between ethyl acetate and water and the separated aqueous phase was washed with ethyl acetate, acidified with 2N HC1 and extracted with ethyl acetate. This organic extract was dried (Na2SO4) and concentrated to ca. 5 ml. The residue was stirred and treated with sodium 2 ethylhexanoate (0.055 g) in ethyl acetate (2 ml) followed by an excess of ether. The resulting precipitate was collected, washed with ether and dried in vacuo to afford the title salt (0.076 g). Vmax (Nujol) 1786 cm-t - lactam), T (D2O) 2.32 and 2.69 (doublets, aromatic protons), 4.45 (d, J 2.5 Hz, C-S H), 6.40 (d, J 6Hz, CHtNHSO2) and 7.62 (s, CH3).

Example 6 Sodium (3R,5R,Z)-2-(2-methylthioureido- ethylidene)-clavam-3-carboxylate A solution of methyl isothiocyanate (0.73 g, 10 mole) in dimethylformamide (2 ml) was added dropwise over 10 min. to a stirred suspension of ACC (0.99 g) in dimethylformamide (8 ml, containing 0.70 ml of triethylamine). After stirring for 2 hr. at room temperature, the clear solution was partitioned between ethyl acetate (250 ml) and brine (200 ml, buffered to pH 2). The aqueous phase was further extracted with ethyl acetate (100 ml), then discarded. The combined organic extracts were washed with brine (4x200 ml, buffered to pH 2), then dried (Na2SO4) and mixed with a solution of sodium 2 - ethylhexanoate (0.21 g) in ethyl acetate (5 ml). The mixture was concentrated to ca 5 ml and the stirred concentrate diluted with ether (15 ml). The precipitated solid was filtered off and dried in a desiccator, yielding title compound (350 mg), Vmax (Nujol) 1786 cm-' (,l - lactam), T (D2O) 4.28 (d, J=2Hz, C-5H), 5.94 (m, C-2' Protons), and 7.11 (s, -NHCH3).

Example 7 Sodium (3 R,5 R,Z)-2-(2-acetamidoethyl idene)clavam-3-carboxylate A suspension of ACC (300 mg) in dimethylformamide (10 ml) was treated with bis(tri - n - butyltin)oxide (0.45 ml). Acetic anhydride (0.15 ml) was added to the solution and the reaction stirred at room temperature for 10 minutes. The solution was partitioned between saturated aqueous (NH4)3SO4 solution containing NaHCO3 (2 g) and ethyl acetate. The aqueous phase was separated, washed with ethyl acetate (x2), acidified with 2N HCI to pH2, resaturated with (NH4)2 SO4, and extracted with ethyl acetate (x3). The combined organic extracts were dried and concentrated to ca 5 ml. A solution of sodium 2 - ethylhexanoate (0.24 g) in ethyl acetate was added and the precipitated salt was filtered off, washed with ethyl acetate and dried to yield title compound (160 mg), the spectral properties of which were similar to those described in Example 1. The title compound having spectral properties similar to those described in Example 1 has also been prepared from ACC using acetic acid with DCC or using acetyl chloride.

Example 8 Sodium (3R,5 R,Z)-2-(2-methylsulphon amidoethylidene)-clavam-3-carboxylate Bis (tri - n - butyltin)oxide (1.30 ml) was added to a stirred suspension of ACC (1.0 g) and 2,4 - dinitrophenyl methanesulphonate (1.30 g) in dimethylformamide (15 ml). After 15 min a further aliquot of bis (tri - n - butyltin)oxide (1.30 ml) was added to the mixture and stirring continued for another 15 min. The reaction mixture was then partitioned between brine (50 ml) and ethyl acetate (100 ml). The separated aqueus phase was washed with ethyl acetate (2x100 ml), acidified to pH 4 with dilute aqueous HCI and washed further with ethyl acetate (4x50 ml). The organic extracts were discarded and the aqueous phase acidified to pH 1.5. The acidic phase was extracted, with ethyl acetate (3x50 ml), then the extracts combined and dried (Na2SO4) and concentrated to 25 ml in vacuo. The concentrate was extracted with brine (5 ml, containing 0.25 g of NaHCO3) and the basic extract washed with ethyl acetate (4x25 ml) to remove residual dimethylformamide. The aqueous phase was then acidified to pH 1.5 and extracted with ethyl acetate(3x25 ml).

The organic extracts were combined and dried (Na2SO4) and concentrated to ca 25 ml in vacuo. A solution of sodium 2 ethylhexanoate (0.20 g) in ethyl acetate (3 ml) was added dropwise, with stirring, to the concentrate and the precipitated solid filtered off and dried in a desiccator, yielding title compound (370 mg), Vrnax (Nujol) 1788 cm (8 - lactam) T (D2O) 4.24 (d, C-5H), 6.16 (d, J=7.5Hz, C2 protons) and 6.94 (s, -SO2CH2).

Example 9 Sodium (3R,5R,Z)-2-(2-ethoxy carbonylaminoethylidene) clavam-3-carboxylate A solution of N - ethoxycarbonylsuccinimide (1.15 g) in dimethylformamide (5 ml) was added dropwise to a suspension of ACC (0.89 g) in dimethylformamide (15 ml, containing 1.57 ml of triethylamine) and the mixture stirred for 2 hr at room temperature. The solution was then partitioned between ethyl acetate (120 ml) and saturated NaCI solution (100 ml, acidified to pH 2 with dilute aqueous HCI). The aqueous layer was extracted with ethyl acetate (100 ml) and the combined organic extracts washed with brine (5x100 ml, buffered to pH 2). The acidic extracts were discarded ~ and the organic phase extracted with aqueous NaHCO3 solution (3x20 ml). The basic extracts were combined, acidified to pH 6 with dilute aqueous HCl and then washed with ethyl acetate (3x100 ml). The organic extracts were discarded and the aqueous phase further acidified to pH 2 and extracted with ethyl acetate (4x75 ml). The organic extracts were combined, dried (Na2SO4) and mixed with a solution of sodium 2 ethylhexanoate (0.22 g) in ethyl acetate (5 ml). The mixture was concentrated to ca 5 ml, then diluted with ether (25 ml). The precipitated solid was filtered off and dried, yielding title compound (520 mg), [a1,+210 (c 0.9, H20), Vmax (Nujol) 1788 cm-t (8 - lactam), T (D2O) 4.30 (d, C-5H) 6.92 (q, J=7Hz, -OCH2CH3) and 8.80 (t, J=7Hz, -OCH2CH3).

Example 10 (3R,5R,Z)-2-(2-Formamidoethylidene) clavam-3-carboxylic acid A solution of 4 - nitrophenyl formate (1.67 g) in tetrahydrofuran (15 ml) was added to a solution of ACC (2.0 g) and NaHCO3 (0.84 g) in water (30 ml) and the mixture stirred at room temperature for 30 min. The mixture was then diluted with brine (50 ml) and washed with ethyl acetate (2x50 ml). The organic extracts were discarded. The aqueous phase was saturated with Na Cl, acidified to pH 2 with dilute aqueous HCl and then extracted with ethyl acetate (10x50 ml). The organic extracts were combined, dried (Na2SO4) and concentrated to ca. 30 ml in vacuo. The title compound was deposited as an amorphous solid (0.40 g) which was filtered off and dried in a desiccator, [al+S30 (c 1.0, DMSO), v,, (Nujol) 1792 cm-l (8 - lactam), # (DMCO-d6) 1.85 (broad singlet, -NHCHO), 1.95 (s,-NHCHO) and 4.26 (d, J=2Hz, C-5H).

Example 11 (3R,5R,Z)-2-(2-Formamidoethylidene) clavam-3-carboxylic acid Bis (tri - n - butyltin)oxide (0.26 ml) was added to a suspension of ACC (0.20 g) and 4 - nitrophenyl formate (0.17 g) in dimethylformamide (3 ml) and the mixture stirred at room temperature for 15 min. The solution was then partitioned between brine (10 ml) and ethyl acetate (25 ml). The organic phase was discarded, then the aqueous layer acidified to pH 5 and washed with ethyl acetate (3x25 ml). The organic extracts were discarded and the aqueous phase acidified to pH 1.5 and further extracted with ethyl acetate (3x25 ml). The extracts were combined, dried (Na2SO4) and concentrated to ca 10 ml. On scratching the sides of the flask, the crystalline title compound (50 mg) was depositet, m.p.

140-141 ; spectral properties resembling those given in Example 10.

Example 12 Sodium (3R,5R,Z)-2-formamido- ethylidene)-clavam 3-carboxylate A solution of 4 - nitrophenyl formate (0.50 g) in tetrahydrofuran (5 ml) was added dropwise to a stirred solution of ACC (0.60 g) and NaHCO3 (0.25 g) in water (10 ml).

After 30 min. the mixture was diluted with brine (20 ml) and washed with ethyl acetate (3x25 ml). The organic extracts were discarded and the aqueous phase acidified to pH 2 with dilute HCl and saturated with NaCl. The acidic mixture was extracted with ethyl acetate (8x25 ml), the extracts combined, dried (Na2SO4) and concentrated to ca 25 ml in vacuo. A solution of sodium 2 - ethylhexanoate (0.25 g) in ethyl acetate (5 ml) was added to the stirred concentrate.

The deposited solid was filtered off and dried, yielding the title compound (330 mg), [α]D+25 (c 1.0, H20), #max (Nujol) 1786 cm-1 ( - lactam), # (DMCO-d6) 1.85 (broad singlet, -NHCHO) and 2.01 (S, -NHCHO), 4.37 (d, C-S H).

Example 13 Sodium (3 R,5 R,Z)-2-(2-formamidoethyl idene)clavam-3-carboxylate A suspension of ACC (0.5 g) in dimethylformamide (10 ml) was treated with bis(tri n - butyltin)oxide (0.75 ml). The solution was cooled to --350 and a solution of DCC (0.75 g) in ethyl acetate (10 ml) was added followed by a solution of formic acid (0.2 ml) in ethyl acetate (10 ml). The solution was allowed to warm slowly to room temperature and additional formic acid (0.1 ml) was added at 20 minute intervals over an 80 minute period. After a further 10 minutes the reaction mixture was filtered and the filtrate was partitioned between ethyl acetate and saturated aqueous (NH4)2SO4 solution containing NaHCO3 (2 g). The organic phase was separated and extracted with saturated aqueous (NH4)2SO4 solution containing NaHCO3 (2 g). The combined aqueous extracts were washed with ethyl acetate (x2), acidified with 2N HCI to pH2, resaturated with (NH4)2SO4 and extracted with ethyl acetate (x3). The combined organic extracts were dried and the solution concentrated to ca 5 ml. A solution of sodium 2 - ethylhexanoate (0.8 g) in ethyl acetate was added and the precipitated salt filtered off (sodium formate). The filtrate was treated with a slight excess of sodium 2 - ethylhexanoate in ethyl acetate and the resulting precipitate was collected, washed with ethyl acetate and dried to yield the title compound (0.185 g). The spectral properties were similar to those described in Example 12.

Example 14 (3R,5R,Z)-2-(2-Phthalimidoethylidene) clavam-3-carboxylic acid N - Ethoxycarbonylphthalimide (0.88 g, finely-ground) was added to a solution of ACC (0.80 g) and NaHCO3 (0.34 g) in water (10 ml). The mixture was stirred vigorously at room temperature for 30 minutes, then filtered and the filtrate acidified to pH 2 with dilute HCI. A gum was deposited from the solution. The gum was washed with water and dried in a vacuum desiccator.

The resulting powder was extracted with hot ethyl acetate (2x10 ml). The organic extracts were combined, then filtered to remove insoluble material and concentrated to ca 2 ml. The product crystallized from the concentrate on standing, yielding title compound (140 mg), imax (MeOH) 239.5 nm (E 11,500), Vmax (Nujol) 1802 cam ' (8-lactam), T (Acetone-d6) 2.10 (s, aromatic protons), 4.19 (d, C--5H) and 5.60 (d, C-2' organic extracts were discarded and the aqueous phase was saturated with NaCI and acidified to pH 2 with dilute HCI. The acidic solution was extracted with ethyl acetate (4x 100 ml) and the extracts were combined and dried (Na2SO4). A solution of sodium 2 - ethylhexanoate (0.50 g) in ethyl acetate (10 ml) was added to the combined extracts, which were then concentrated to ca 15 ml. The stirred concentrate was diluted with ether (15 ml) and the deposited solid filtered off and dried to yield the title compound (1 g), [α]D+24 (c 1.0, H2=), #max (Nujol), 1790 cm-1 (ss - lactam), # (D2=) 4.18 (d, C--5H), 6.15 (m, -C112-NM- and tetrahydropyran 2 - protons), and 8.3-8.7 (tetrahydropyran protons).

Example 19 Sodium (3 R,5 R,Z)-2-(2-formamidoethyl idene)clavam-3-carboxylate.

A suspension of ACC (0.3 g) in demethylformamide (5 ml) was treated with formic acid (0.2 ml) followed by DCC (0.45 g) in ethyl acetate (5 ml). After 45 minutes the reaction mixture was filtered and the filtrate was partitioned between ethyl acetate and saturated aqueous (NH4)2 SO4 solution containing NaHCO3 (2 g). The organic phase was separated and extracted with saturated aqueous (NH4)2SO4 solution containing NaHCO3 (2 g). The combined aqueous extracts were washed with ethyl acetate (x2), acidified with 2N HCI to pH2, resaturated with (NH4)2SO4 and extracted with ethyl acetate (x3). The organic extracts were dried and concentrated to ca 5 ml. Excess sodium 2 - ethylhexanoate in ethyl acetate was added and the resulting precipitate was collected, washed with ethyl acetate and dried to yield the title compound (195 mg), the spectral properties of which werer similar to those described in Example 12.

Example 20 Methyl (3R,5R,Z)-2-(2-acetamidoethyl idene)clavam-3-carboxylate A solution of methyl (3R,5R,Z) - 2 - (2 aminoethylidene) - clavam - 3 carboxylate (100 mg) in ethyl acetate (40 ml) was treated with a solution of acetic anhydride (0.1 ml) in ethyl acetate (5 ml).

The mixture was stood at ambient temperature for 20 minutes and was then washed successively with 0.5N aqueous NaHCO3 and 0.2N HCI. The acidic washings were saturated with (NH4)2SO4 and back extracted with ethyl acetate. The combined ethyl acetate extracts were dried and evaporated to give the title ester as an oil (50 mg), #max (CHBr3), 1798 cm-1 (ss lactam), # (CDCl3) 4.30 (d, J 3Hz, C-5H), 6.20 (s, CO2CH3), and 8.03 (s, NHCOCH3).

Example 21 B enzyl (3 R,S R,Z)-2-(2-acetamidoethyl idene)clavam-3-carboxylate A solution of BAC (300 mg) in ethyl acetate (20 ml) was treated with a solution of acetic anhydride (0.1 ml) in ethyl acetate (10 ml). After 20 minutes and 30 minutes, further portions of acetic anhydride (0.05 and 0.01 ml) in ethyl acetate (2 ml) were added. The mixture was stirred for a further 10 minutes after the last addition and was then washe successively with 0.05N HCl, 0.5N aqueous NaHCO3 and water. The organic solution was dried (MgSO4) and evaporated to afford the title ester as a crystalline solid (190 mg), Vmax (CHBr3) 1795 cm-l (8 - lactam), T (CDCl3, 4.31 (d, J 3 Hz, C-S H), 6.10 (m, CH2NH) and 8.06 (s, NHCOCH3).

The title ester having similar spectral properties was also prepared from BAC using acetyl chloride or using acetic acid with DCC.

Example 22 B enzyl (3 R,5 R,Z)-2-(2-formamidoethyl idene)clavam-3-carboxylate A solution of BAC (10 g) in ethyl acetate (350 ml) was stirred and treated with a solution of DCC (5 g) in ethyl acetate (50 ml) followed by a solution of formic acid (1.5 ml) in ethyl acetate (50 ml). After 45 minutes the mixture was filtered and the filtrate washed successively with 0.05N HCI, 0.5N aqueous NaHCO3 and water. The organic solution was dried and evaporated to give an oil which was chromatographed on silica gel with ethyl acetate as eluant to afford the title ester as an oil (1.01 g), [α]D23+45 (c 1.0; CHCl3), #max (CHBr3), 1796 cm-1 (ss - lactam), # (CDCl3) 1.86 (s, -CHO9, 2.60 (s, saromatic protons), 4,27(d, J 3 Hz, C-5 H), 4.76 (s, CH2Ph) and 6.03 (m, CH,NH).

Example 23 Sodium (3R,5R,Z)-2-(2-acetamidoethyl- idene)clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - (2 acetamidoethylidene) - clavam - 3 carboxylate (160 mg) and NaHCO3 (35 mg) in ethanol (10 ml) and water (2 ml) was hydrogenated over 10% palladium on carbon (60 mg) at atmospheric pressure and ambient temperature for 30 minutes. The catalyst was removed by filtration and the solvents by evaporation to afford an oil. The oil was partitioned between brine acidified with 2N HCI and ethyl acetate. The aqueous phase was extracted with the ethyl acetate and the combined organic extracts dried (MgSO4) and concentrated to ca. 5 ml. The residue was stirred and treated with sodium 2 - ethylhexanoate (50 mg) in ethyl acetate (1 ml). The resulting precipitate was collected washed and dried to afford the title salt (30 mg). The i.r. and n.m.r. spectra of the product resembled those described in Example 1.

Example 24 Sodium (3R,5 R,Z)-2-(2-formamidoethyl- idene)clavam-3-carboxylate Following the procedure of Example 23, benzyl (3R,5R,Z) - 2 - (2 - formamidoethylidene) - clavam - 3 - carboxylate (160 mg) was hydrogenated to yield the title salt (40 mg). The i.r. and n.m.r. spectra of the product resembled those described in Example 12.

Example 25 Methyl (3R,SR,Z)-2-formamidoethyl- idene)-clavam-3-carboxylate.

A solution of diazomethane (ca. 0.5 g) in ether (20 ml) was added portionwise over 2 hr to a stirred, ice-cooled suspension of (3R,5R,Z) - 2 - (2 - formamidoethylidene) clavam - 3 - carboxylic acid (0.34 g) in ethyl acetate (10 ml). After addition was complete, the mixture was stirred for a further hour. The solution was then purged with nitrogen for 10 mins, filtered and the filtrate concentrated in vacuo to give the title ester as an oil (330 mg), #max (CHBr3), 1798 cm-l (8 - lactam), T (CDCl3) 1.84 (s, NHCHO), 3.92 (broad singlet, -NHCHO), 4.27 (d, J 2Hz, C--5H), and 6.19 (s -OCH). Example 26 Acetoxymethyl (3R,5R,Z)-2-(2-formamido ethylidene)-clavam-3 -carboxylate Chloromethyl acetate (0.72 ml) was added to a solution of sodium iodide (2.4 g) in acetone (10 ml) and the mixture stirred at room temperature for 2 hr. The mixture was then concentrated in vacuo and the residue partitioned between water (10 ml) and petroleum ether (bp 60-80 ) (10 ml).

The organic layer was dried (Na2SO4) and added to a stirred solution of sodium (3R,5R,Z) - 2 - (2 - formamidoethylidene) clavam - 3 - carboxylate (1.25 g) in dimethyl sulphoxide (10 ml). After stirring for 10 min., the mixture was partitioned between brine (50 ml) and ethyl acetate (50 ml). The organic layer was separated, washed with water (2x50 ml), dried (Na2SO4) and concentrated in vacuo to yield the title ester (320 mg), #max (CHBr3), 1796 cm-1 (ss - lactam), # (CDCl3) 1.84 (D, -N H C H O ), 3 . 9 8 ( b r o a d s i n g l e t , -NHCHO), 4.15-4.30 (m, -OCH2O- and C-S H), and 7.88 (s, -CM3).

Example 27 Benzyl (3R,5 R,Z)-2-(2-nicotinamido ethylidene)-clavam-3-carboxylate A solution of DCC (1.65 g) and BAC (2.3 g) in ethyl acetate (75 ml) was added to a suspension of nicotinic acid (0.99 g) in ethyl acetate (75 ml) and the mixture stirred for 2 hr at room temperature. The mixture was then filtered and the filtrate washed with 0.05 N aqueous HCI (100 ml), 0.5 N aqueous NaHCO3 solution (2x 100 ml) and water (100 ml) and dried (Na2SO4). The organic solution was then concentrated in vacuo and the residue passed down a colum of silica gel (100 g). The column was eluted initially with ethyl acetate:petroleum ether (1:1) and then with ethyl acetate alone. Those fractions containing the product were combined and concentrated in vacuo to yield the title ester (390 mg), #max (CHBr3) 1790 cm-1 (ss-lactam), # (CDCl3) 1.01, 1.24 and 1.87 (pyridyl protons), 3.40 (broad singlet, -NHCO-) and 4.28 (d, C--5H).

Example 28 Sodium (3R,5R,Z)-2-(2-nicotinamidoethyl- idene)clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - (2 nicotinamidoethylidene) clavam - 3 carboxylate (0.59 g) in ethanol (80 ml) was hydrogenated over palladium on carbon (10%, 0.20 g) for 30 min. The mixture was filtered through Kieselguhr, the filter pad washed with ethanol and the combined filtrate and washings concentrated to ca 20 ml. A solution of sodium 2 - ethylhexanoate (0.25 g) in ethanol (10 ml) was added dropwise to the concentrate, which was then evaporated to ca 5 ml and diluted with ether (10 ml). The precipitated solid was filtered off, washed with ether and dried to yield the title compound (390 mg) #max (pH6 buffer) 256.5 (# 4.400) and 262 nm (# 4,500), v,,,, (Nujol) 1776 cm-l ( - lactam), T (D2O) 1.08, 1.24, 1.78 and 2.38 (pyridyl protons) and 4.18 (d, C-S H).

Example 29 Benzyl (3R,5R,Z)-2-(2-phenoxyacetamido- ethylidene)clavam-3 -carboxylate A solution of DCC (3.09 g) in ethyl acetate (50 ml) was added to a solution of phenoxyacetic acid (2.32 g) and BAC (4.33 g) in ethyl acetate (150 ml) and the mixture stirred at room temperature for I hr. The mixture was then filtered and the filtrate washed with 0.05 N aqueous HCI (100 ml), saturated aqueous NaHCO3 solution (2x50 ml) and water (50 ml) and dried (Na2SO4).

The organic solution was then concentrated in vacuo and the residue passed down a column of silica gel (120 g). The column was eluted with ethyl acetate:petroleum ether.

Those fractions containing the product were combined and concentrated to yield the title ester as an oil (710 mg), #max (CHBr3) 1798 cm-1 (ss - lactam), # (CDCl3) 2.6-3.2 (m, phenyl protons), 3.30 (broad singlet, -CONH-), 4.38 (d, C--5H), and 5.50 (s,-COCM2O-).

Example 30 Sodium (3 R,5 R,Z)-2-(2-phenoxyacetamido- ethylidene)clavam-3 -carboxylate Following the procedure of Example 28 benzyl (3R,5R,Z) - 2 - (2 phenoxyacetamidoethylidene)clavam - 3 carboxylate (0.63 g) was hydrogenated to yield the title compound (290 mg), #max (Nujol) 1782 cm-l (8 - lactam), T (D2O) 2.5-3.1 (m, phenyl protons), 4.37 (d, C--5H), and 5.47 (s, -COCH2O-).

Example 31 Benzyl (3R,5R,Z)-2-(2-methylureido ethylidene)clavam-3-carboxylate Bis (tri - n - butyltin) oxide (3.6 ml) was added to a stirred solution of methyl isocyanate (1.14 g) and BAC (4.32 g) in ethyl acetate (150 ml). After 1 hr a second aliquot of methyl isocyanate (0.70 ml) was added to the reaction mixture and stirring continued for a further 30 min. The solution was then concentrated in vacuo and the residue passed down a column of silica gel using ethyl acetate as eluent, to give the title ester (1.07 g), #max (CHBr3) 1796 cm-1, (ss lactam), # (CDCl3), 4.31 (D, J 2 Hz, C-5H), 6,16 (t, J 7Hz, C-2 protons), and 7.26 (d, -NHCH3).

Example 32 B enzyl (3 R,5 R,Z)-2- [2-a-(benzyloxy- carbonylamino)acetamidoethylidene] clavam-3 -carboxylate A solution of N - benzyloxycarbonyl glycine (2.09 g) in ethyl acetate (50 ml) was added to a solution of DCC (2.06 g) and BAC (2.88 g) in ethyl acetate (150 ml) and the mixture stirred at room temperature for 90 min. The mixture was filtered- and the filtrate washed with 0.05N aqueous HCI (2x 100 ml), saturated aqueous NaHCO3 solution (2x 100 ml) and water (100 ml). The organic solution was dried (Na2SO4) and concentrated in vacuo. The residue was chromatographed on silica gel preparative plates, using ethyl acetate:petroleum ether (3:1) eluant, to give the title compound (880 mg), m,, (CMBr3) 1790 cm-' (8 - lactam), (CDCl3) 2.67 (S, phenyl protons), 3.86 and 4.52 (broad singlets, -NHCO-), 4.35 (d, J=2Hz, C--5H), and 6.21 (d, -COCH2NM-).

Example 33 (3 R,5 R,Z)-2-(2-a-Aminoacetamidoethyl- idene)clavam-3-carboxylic acid A solution of benzyl (3R,5R,Z)-2-[2-a- (benzyloxycarbonylamino) - acetamido ethylidene] clavam - 3 - carboxylate (0.78 g) in ethanol (80 ml) was hydrogenated over palladium on carbon (10%, 1.30 g) for 30 min. The reaction mixture was then diluted with water (50 ml) and filtered through Kieselguhr. The filtrate was concentrated under reduced pressure on a rotatry evaporator to remove the organic solvent.

The residual aqueous solution was washed with ethyl acetate (2x30 ml) and lyophilized to give the title compound (350 mg), umax (Nujol) 1786 cm-' (8 - lactam), T (D2O) 4.27 (d, C-5H) 6.08 (d, J=7Hz, C-2 protons), + 6.23. (S, -COCH2NM2).

Example 34 Sodium (3R,5R,Z)-2-[2-α-(benzyloxy- carbonyl-amino)acetamidoethylidene] clavam-3-carboxylate Bis (tri - n - butyltin) oxide (1.30 ml) was added to a stirred suspension of ACC (0.99 g) and bis (N - benzyloxycarbonylglycine) anhydride (2.0 g) in dimethyl formamide (10 ml). After stirring for 30 min, the mixture was diluted with brine (75 ml) and the pH adjusted to 7.5 with aqueous NaHCO3 solution. The basic mixture was washed with ethyl acetate (5x100 ml) and the organic extracts discarded. The aqueous solution was then acidified to pH 2 with 2N aqueous HCI and extracted with ethyl acetate (3x75 ml). The organic extracts were dried (Na2SO4) and mixed with a solution of sodium 2 - ethylhexanoate (0.50 g) in ethyl acetate (20 ml). The cloudy solution was concentrated to ca 20 ml, then diluted with ether (20 ml). The precipitated solid was filtered off and dried to give the title compound (1.32 g), #max (Nujol) 1785 cm-1 (ss - lactam), # (D2O) 2.55 (s, phenyl protons), 4.29 (d, J=2HZ, C-5H), and 6.06.2 (m, -CH2NMCOCH2-).

Example 35 Benzyl (3R,5R,Z)-2-[2-D-cr-(benzyl- oxycarbonylamino)-phenylacetamido ethylidene]-clavam-3-carboxylate DCC (3.70 g) was added to a solution of D - (N - benzyloxycarbonyl) phenylglycine (5.13 g) and BAC (5.18 g) in ethyl acetate (250 ml) and the mixture stirred at room temperature for 2 hr. The mixture was then filtered and the filtrate washed successively with 0.05 N aqueous HCl (50 ml), 0.5 N aqueous NaHCO3 solution (50 ml), and brine (50 ml). The organic solution was dried (Na2SO4) and concentrated in vacuo. The residue was passed down a column of silica gel (150 g) using ethyl acetate:petroleum ether (1:1) eluent, to give the title compound (890 mg), #max (CHB3) 1795 cm-1 (ss - lactam), # (CDCl3) 2.65 (phenyl protons), 3.80 (d, -CH . Ph . NH-), 4.12 (broad singlet, -CH2NHCo-) and 4.43 (C-5H).

Example 36 Benzyl (3R,5R,Z)-2-{2-[3-(4-methoxy benzyloxycarbonyl)-propionamido] ethylidene}clavam-3-carboxylate To a stirred ethyl acetate solution (60 ml) containing BAC (ca 6 mmole) was added a solution of DCC (1.5 g) in ethyl acetate (25 ml) followed by 3 - (4 - methoxybenzyloxycarbonyl)propionic acid (2.0 g) in ethyl acetate (50 ml). The mixture was stirred at ambient temperature for 1 hour and was then filtered. The filtrate was washed successively with 0.1N HCI, saturated aqueous NaHCO3 and water. The dried organic solution was evaporated to an oil which was chromatographed on silica gel to afford the title ester as a solid (1.3 g); [α]D20+30 (c 1.7; CHCl3), 1796 (ss - lactam) 1730 and 1740 cm-1 (esters), # (CDCl3) 4.29 (broad s, NH), 4.33 (d, J 2 Hz, C-S H) and 4.80 (s, OCH3).

Example 37 Disodium (3R,5R,Z)-2-[2-carboxyl atopropionamido)-ethylidene]-clavam 3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - (2 [3 - (4 - methoxybenzyloxycarbonyl) propionamido]ethylideneNclavam - 3 carboxylate (0.67 g) in ethanol (150 ml) was hydrogenated at atmospheric pressure and ambient temperature over 10% palladium on carbon (0.18 g) for 1 hour. The catalyst was removed by filtration, washed with ethanol and the combined filtrates concentrated to ca 20 ml. The residue was stirred and treated with a solution of sodium 2 - ethylhexanoate (0.4 g) in ethanol (5 ml) followed by ether (30 ml). The resulting precipitate was collected, washed and dried to yield the title salt (0.35 g), [al20+270 (c 0.78; H2O), P,,,, (Nujol) 1776 cm-' (8 lactam) T (D2O) 4.29 (d, J 2 Hz, C-S H), 6.17 (d, J 7 Hz, -CH2NH) and 7.50 (s, CH2CH2).

Example 38 Benzyl (3R,5R,Z)-2-[2-(3-carboxy propionamido)-ethyliden] clavam 3-carboxylate To a stirred ethyl acetate solution (50 ml) containing BAC (ca 5 mmole) was added a solution of succinic anhydride (0.52 g) in ethyl acetate (20 ml). The mixture was stirred at ambient temperature for 40 mins and was then shaken for 2 mins with 0.5 N aqueous NaHCO3. The separated' organic phase was extracted with further 0.5 N aqueous NaHCO3 and the combined aqueous phases were acidified with 2N HCI and extracted with ethyl acetate. The dried ethyl acetate extract was evaporated to give an oil which solidified on trituration with ether to afford the title ester (0.81 g), [α]D20+40 (c 1.19; CHCl3), #max (CHBr3) 1790 cm-1 (ss - lactam), # (CDCl3) 3.62 (broad, NH), 4.31 (d, J 2 Hz, C-S H) and 7.2-7.7 (m, CH2CH2).

Example 39 Disodium (3 R,5 R,Z)-2- [2-(3-carboxyl atopropionamido)-ethylidene]-clavam 3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (3 - carboxypropionamido) - ethylidene]clavam - 3 - carboxylate (0.46 g) in ethanol (100 ml) was hydrogenated and worked up according to the method described in Example 37 to yield the title salt (0.34 g). The spectroscopic properties of the product resembled those described in Example 37.

Example 40 B enzyl (3 R,5 R,Z)-2- [2-(a-acetamidoacet- amido)ethylidenel-clavam-3-carboxylate A solution of BAC (1.5 g) in ethyl acetate (50 ml) was treated with a solution of DCC (1.08 g) in ethyl acetate (25 ml) followed by N - acetylglycine (0.61 g) in N,N dimethylformamide (10 ml). The mixture was stirred for 2 hours, treated with further N - acetylglycine (0.2 g) and DCC (0.45 g) and stirred for a further 2 hours.

Precipitated solid was removed by filtration and the resulting solution washed successively with N HCI, 0.5 N aqueous NaHCO3 and water. The dried organic solution was evaporated to afford the title ester (0.58 g), [α]D20+39 (c 0.95; CHCl), #max CHBr3), 1796 cm-1 (ss - lactam), # (CDCl3) 4.28 (d, J 2 Hz, C-S H), 5.9-6.2 (m, CH2NHCOCH2) and 7.96 (s, CH3).

Example 41 Sodium (3R,5R,Z)-2-[2-(α-aacetamidoacet- amido)ethylidene]-clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 [2 - (α - acetamidoacetamido)ethylidene]clavam - 3 - carboxylate (0.5 g) in ethanol (50 ml) was hydrogenated for 15 mins at atmospheric pressure and ambient temperature over 10% palladium on carbon (0.2 g). The catalyst was removed by filtration through Kieselguhr and the filtrate concentrated to ca 5 ml. The residue was treated with a solution of sodium 2 ethylhexanoate (0.2 g) in ethyl acetate (5 ml) followed by ether (ca 50 ml). The resulting precipitate was collected, washed with ether and dried in vacuo to afford the title salt (0.3 g), [α]D20+26 (c 0.98; H2O), #max (Nujol) 1780 cm-1 (ss - lactam) # (D2O) 4.28 (d, J 2 Hz, C-S H), 6.16 (s, CH2NHCOCH3) and 7.96 (s, CH3).

Example 42 Benzyl (3R,5R,Z)-2-[2-(α,α-dichloroacet- amido)ethylidene]-clavam-3-carboxylate A solution of BAC (0.58 g) and pyridine (0.41 ml) in ethyl acetate (50 ml) was treated with a solution of dichloroacetyl chloride (0.5 ml) in ethyl acetate (15 ml). After 10 mins the reaction mixture was washed successively with 0.5N HCI, 0.5N aqueous NaHCO3 and water. The dried organic solution was evaporated to give an oil which was chromatographed on silica gel to afford the title ester (0.29 g), [α]D20+43 (e 0.86; CHCl3), #max (CHBr3) 1792 cm-1 (ss - lactam), # (CDCl3) 3.30 (broad, NH), 4.10 (s, CHCl3), and 4.30 (d, J 2 Hz, C-5 H).

Example 43 Sodium (3R,5R,Z)-2-[2-α,α-dichloroacet- amido)ethylidene]-clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (α,α - dichloroacetamido)ethylidene] clavam - 3 - carboxylate (0.62 g) in ethanol (50 ml) was hydrogenated and worked up according to the method describend in Example 41 to afford the title salt (0.305 g), [α]D20+25 (c 1.15; H2=), #max (Nujol), 1728 cm-1 (ss - lactam), # (D2O) 3.70 (s, CHCl2), 4.23 (d, J 2 Hz, C- 5 H) and 6.03 (d, J 7 Hz, CH2NHCO).

Example 44 Benzyl (3R,5R,Z)-2-[2-(α-cyanoacetamido)- ethylidene] clavam-3-carboxylate A stirred solution of BAC (1.5 g) in ethyl acetate (100 ml) was treated with DCC (1.37 g) in ethyl acetate (50 ml) followed by cyanoacetic acid (0.56 g) in ethyl acetate (50 ml). After 45 mins, further portions of DCC (0.2 g) and cyanoacetic acid (0.1 g) were added and the mixture was stirred for an additional 30 mins. Precipitated solid was removed by filtration and the resulting organic solution was washed successively with N HCI, 0.5 N aqueous NaHCO3 and water. The dried solution was evaporated to an oil which was chromatographed on silica gel to afford the title ester (0.48 g), [α]D20+52 (c 0.68; ChCl3), #max (CHBr3) 1794 cm-1 (ss lactam), # (CDCl3) 3.50 (broad, NH), 4.30 (D, J 2 Hz, C-5 H), 6.06 (t, J 6 Hz, CH2 NHCO) and 6.69 (s, CH2CN).

Example 45 Sodium (3R,5R,Z)-2-[2-(α-cyanoacet- amido)ethylidene]clava-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 [2 - (α - cyanoacetamido) - ethylidene] clavam - 3 - carboxylate (0.35 g) in ethanol (35 ml) was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.23 g), [α]D20+27 (c 0.79; H2O), #max (Nujol), 1778 cm-1 (ss - lactam), # (D2O), 4.27 (d, J 2 Jz, C-S H) and 6.10 (d, J 7 Hz, CH2NHCO).

Example 46 Benzyl (3R,%R,Z)-2-[2-(α-methoxyacet- amido)ethylidene]-clavam-3-carboxylate A solution of BAC (1.5 g) in ethyl acetate (50 ml) was treated with DCC (1.05 g) in ethyl acetate (25 ml) and methoxyacetic acid (0.416 g) in ethyl acetate (25 ml). After 45 mins the mixture was filtered and the filtrate washed successively with N HCI, 0.5 N aqueous NaHCO3 and water. The dried organic solution was evaporated to give an oil which was chromatographed on silica gel to afford the title ester (0.93 g) [α]D20+42 (c 1.53; CHCl3), m,, (CHBr3), 1790 cm-' (ss lactam, # (CDCl3) 3.42 (broad, NH), 4.33 (d, J 2 Hz, C-5 H), 6.16 (s, CH2OCH3) and 6.63 (s, OCH3).

Ecample 47 Sodium (3R,5R,Z)-2-[2-α-methoxyacet- amido)ethylidene]-clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (α - methoxyacetamido)ehthylidene- clavam - 3 - carboxylate (0.67 g) in ethanol (50 ml) was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.465 g), [α]D20+30 (c 1.22; H2O), #max (Nujol, 1780 cm-1 (ss - lactam), # (D2O) 4.28 (d, J 5 Hz, C-S H), 6.04 (s, CH2OCH3) and 6.60 (s, OCH3).

Example 48 Benzyl (3R,5R,Z)-2-[2-(α-hydroxyacet- amido)ethylidene]-clavam-3-carboxylate A stirred solution of BAC (1.5 g) in ethyl acetate (100 ml) was treated with a solution of DCC (1.07 g) in ethyl acetate (25 ml) followed by glycollic acid (0.4 g). After 45 mins further portions of DCC (0.6 g) and glycollic acid (0.3 g) were added and the mixture was stirred for an additional 40 mins. Precipitated solid was removed by filtration and the resulting solution was washed successively with 0.5N HCI, 0.5N aqueous NaHCO3 and water. The dried solution was evaporated to an oil which was chromatographed on silica gel to afford the title ester (0.21 g) [α]D20+45 (c 0.74; CHCl3), #max (CHBr3) 1790 cm-1 (ss - lactam), # (CDCl3) 3.24 (broad, NH), 4.32 (d, J 2 Hz, C-5), 5.99 (s, CH2OH) and 6.34 (broad, OH).

Example 49 Benzyl (3r,5R,Z)-2-[2-(α-azidoacet- amido)ethylidene]calvam-3-carboxylate A stirred suspension of potassium azidoacetate (0.723 g) in dichloromethane (5 ml) containing N,N - dimethylformamide (4 drops) at 0 was treated with a solution of oxalyl chloride (0.43 ml) in dichloromethane (5 ml). The mixture was allowed to reach ambient temperature and was stirred for 5 hours. The resulting suspension was poured into a solution of BAC (1.5 g) and pyridine (2.04 ml) in ethyl acetate (25 ml) at 00. After 20 mins the mixture was partitioned between 0.5 N HCI and ethyl acetate. The separated organic phase was washed successively with 0.1 N HCI, 0.5 N aqueous NaHCO3 and water.

The dried solution was evaporated and the residue chromatographed on silica gel to afford the title ester (0.99 g), [a]20+390 (e 1.15; CHCl2), p,,,, (CHBr3) 1794 cm-i (h- lactam), T (CDCl2) 3.58 (broad, NH), 4.27 (d, J 2 Hz, C-S H) and 6.03 (s, CH2N3).

Example 50 Sodium (3 R,5 R,Z)-2- [2-(a-aminoacet amido)ethylidene]clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (a - azidoethylidene] clavam-3-carboxylate (0.5 g) in ethanol (50 ml) was hydrogenated at atmospheric pressure and ambient temperature over 10% palladium on carbon (1.3 g) for 15 min. Work-up according to the method described in Example 41 afforded the title salt (0.11 g), PmaX (Nujol) 1776 cm-' (8 - lactam), T (D2O) 4.29 (d, J 2 Hz, C-S H), 6.10 (d, J 7 Hz, CH,NHCO) and 6.50 (s, CH2NH2) Example 51 Benzyl (3R,5R,Z)-2-[2-(α-bromoacet- amido)ethylidene]clavam-3-carboxylate A stirred solution of BAC (1.53 g) in ethyl acetate (50 ml) at 0 was treated with pyridine (1.03 ml) followed by bromoacetyl bromide (0.45 ml). After 10 mins the mixture was washed successively with N MCI, 0.5 N aqueous NaHCO3 and water.

The dried solution was evaporated and the residue chromatographed on silica gel to afford the title ester (0.87 g), [α]D20+42 (c 1.02; CHCl3), #max (CHBr3) 1796 cm-1 (ss lactam), T (CDCl3) 3.45 (broad, NH), 4.28 (d, J 2 Hz, C-S H) and 6.14 (s, CH2Br).

Example 52 Sodium (3R,5R,Z)-2-(2-acetamido ethylidene)clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (α - bromoacetamido) - ethylidene] clavam - 3 - carboxylate (0.45 g) in ethanol (50 ml) was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.28 g).

The spectroscopic properties of the product resembled those described in Example 1.

Example 53 Benzyl (3R,5R,Z)-2-(2-oxamidoethyl- idene)clavam-3-carboxylate A stirred solution of BAC (2.0 g) in ethyl acetate (30 ml) was treated with a solution of oxamide (0.8 g) in N,N - dimethylformamide (15 ml) followed by DCC (1.5 g) in ethyl acetate (10 ml). After 2 hours further portions of oxamide (0.4 g) and DCC (0.75 g) were added and the mixture stirred for an additional 2 hours. The mixture was then partitioned between water and ethyl acetate and filtered. The separated organic phase was washed with water and with brine. The dried solution was evaporated and the residue chromatographed on silica gel to afford the title ester (0.984 g), p,,,, (Nujol), 1790 cm-' (p - lactam), T (DMSO-d6) 1.21 (t, J 6 Hz, NH), 1.97 and 2.33 (broad singlets, NH2), 4.26 (d, J 2 Hz, C-5 H) and 6.16 (t, J 6Hz, CH2NH).

Example 54 (3R,5R,Z)-2-(2-Oxamidoethylidene) clavam-3-carboxylic acid A solution of benzyl (3R,5R,Z) - 2 - (2 oxamidoethylidene) - clavam - 3 carboxylate (0.75 g) in ethyl acetate (20 ml) - ethanol (20 ml) was hydrogenated at atmospheric pressure and ambient temperature for 15 mins over 10% palladium on carbon (0.4 g). The catalyst was removed by filtration through kieselguhr and the filtrate concentrated to ca 15 ml.

The resulting precipitated material was collected, washed with ether and dried to give the title acid (0.162 g), p,,,, (Nujol), 1792 cm-' (p - lactam), T (DMSO-d6) 1.22 (t, J 6 Hz, NH), 1.98 and 2.26 (singlets, NH2), 4.29 (d, J 2 Hz, C--5 H) and 6.16 (t, J 6 Hz, CH2NH).

The filtrate from the above crystallisation was treated with a solution of sodium 2 ethylhexanoate (0.45 g) in ethanol (5 ml) and the resulting suspension diluted with ether. The solid was collected, washed and dried to give the sodium salt of the title acid (0.325 g), [α]D20+23 (c 1.07; H2O), #max (Nujol) 1776 cm-1 (ss - lactam), # (D2O) 4.25 (d, J 2 Hz, C-S H) and 6.02 (d, J 7 Hz, CH2NH).

Example 55 Benzyl (3 R,5R,Z)-2-[2-(a-formamido- acetamido)ethylidene]clavam-3-carboxylate A stirred solution of BAC (1.7 g) in dichloromethane (10 ml) was treated with DCC (1.4 g) in dichloromethane (5 ml) followed by N - formylglycine (0.67 g) in N,N - dimethylformamide (10 ml).

After 1 hour, further portions of DCC (0.35 g) and N - formylglycine (0.17 g) were added and the mixture was stirred for an additional 30 mins. The mixture was filtered and the filtrate partitioned between ethyl acetate and brine. The organic phase was washed with brine, dried and evaporated to an oil which was chromatographed in silica gel to afford an oil. The oil was recrystallised from ethyl acetate to yield the title ester (0.948 g) v,, (Nujol), 1800 cm (ss - lactam), # (DMXO-d6) 1.87 (broad, NHCOCH2NH), 1.89, (s, NHCHO) and 4.27 (d, J 2 Hz, C-5 H).

Example 56 Sodium (3R,5R,Z)-2-[2-(α-formamido- acetamido)ethylidene]clavam-3-carboxylate A solution of benzyl (3R,%R,Z) - 2 - [2 (α - formamidoacetamido) - ethylidene]clavam - 3 - carboxylate (0.84 g) in ethyl acetate (20 ml) - ethanol (20 ml) was hydrogenated and worked up according to the method described in Examnle 41 to afford the title salt (0.64 g) [α]D20+37 (c1.14; H2O), #max (Nujol) 1782 cm-1 (ss - lactam), # (D2O) 1.80 (S, NHCHO), 4.25 (d,J 2 Hz, C-S H).

Example 57 Sodium (3R,5 R,Z)-2-[2-(a-hydroxyacet- amido)ethylidene] clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (α - hydroxyacetamido - ethylidene]calvam - 3 - carboxylate (0.11 g) in ethanol (20 ml) was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.07 g), [α]D20+24 (c 0.53; H2=), #max (Nujol) 1776 cm-1 (ss - lactam), # (D2O) 4.26 d, J 3 Hz, C-S H), 6.05 (d, J 7 Hz, CH2NHCO) and 5.94 (s, CH2OH).

Example 58 Sodium (3R,5R,Z)-2- [2-(a-bromoacet amido)ethylidene] clavam-3-carboxylate A solution of benzyl (3R,5R,Z) - 2 - [2 (bromoacetamido) - ethylidene]clavam - 3 - carboxylate (0.65 g) in ethyl acetate (20 ml) - ethanol (20 ml) was hydrogenated for 5 min at atmospheric pressure and ambient temperature over 10% palladium on carbon (0.325 g). The catalyst was removed by filtration through kieselguhr and the filtrate concentrated to ca 10 ml. The stirred residue was treated with sodium 2 ethylhexanoate (0.22 g) in ethyl acetate (5 ml) followed by an excess of ether. The resulting precipitate was collected, washed and dried to give the title salt (0.41 g), +31 (c 0.9; H2O), #max (Nujol) 1778 cm-1 (ss - lactam), # (D2O) 4.27 (d, J 3 Hz, C- 5 H), 6.10 (d, J 7 Hz, CH2NHCO) and 6.12 (s, CH2Br).

Example 59 (3 R,5 R,Z)-2- [2-(a-Aminoacetamido)- etyhlidene]clavam-3-carboxylic acid A solution of sodium (3R,5R,Z) - 2 -[2 α - (benuyloxycarbonylamino)acetamidoathylidene]clavam - 3 - carboxylate (0.40 g) in water (10 ml) was acidified to pH 2 and extracted with ethyl acetate (2x 10 ml). The organic extracts were combined, dried (Na2SO4) and partially concentrated (to 9 ml) in vacuo. The concentrated solution was diluted with ethanol (3 ml) and hydrogenated over palladium on carbon (10%, 0;45 g) for 1 hr. The reaction mixture was shaken with water (5 ml) and filtered through kieselguhr. The filtrate was washed with ethyl acetate (15 ml), the organic layer discarded and the aqueous phase lyophilized to yield the title compound (140 mg), whose -spectroscopic properties resembled those given in Example 33.

Example 60 Benzyl (3R,5R,Z)-2-(2-phenylgly- oxamidoethylidene)-clavam-3-carboxylate A solution of DCC (1.13 g) in dry tetrahydrofuran (20 ml) was added to a solution of phenylglyoxylic acid (0.75 g) and BAC (1.44 g) in tetrahydrofuran (30 ml) and the mixture stirred on an ice-water bath for 90 min. The mixture was filtered and the filtrate concentrated in vacuo. The residue was chromatographed on a silica gel column, using ethyl acetate: petroleum ether (1.2) eluent, togive the title ester (460 mg), #max (CHBr3) 1794 cm-1 (ss - lactam), # (CDCl3) 1.66 and 2.3-2.6 (m,-COPh), 4.29 (d, J 2Hz, C-5 H), and 5,96 (t, J= 7Hz, C-2' protons).

Example 61 Sodium (3R,5R,Z)-2-(2-phenylgly- oxamidoethylidene)-clavam-3-carboxylate A solution of 4- nitrophenyl phenyl glyoxylate (0.27 g) in tetrahydrofuran (2 ml) was added to a solution of ACC (0.20 g) and NaHCI3 (85 mg) in water (2 ml) ad the mixture stirred rapidly at room temperature for 20 min. The mixture was diluted with brine (10 ml) and washed with ethyl acetate (2x 10 ml). The organic extracts were discarded and the aqueous phase acidified to pH 4 with dilute aqueous MCI. The acidic solution was extracted with ethyl acetate, the organic extracts dried (Na2SO4) and added to a solution of sodium 2 ethylhexanoate (80 mg) in ethyl acetate. The cloudy solution was concentrated to ca 5 ml and diluted with ether (20 ml). The deposited solid was filtered off, giving the title compound (80 mg), #max (Nujol)1780 cm-1 (ss - lactam), # (D2O) 2.30 and 2.2-2.6 (m, phenyl protons), 4.25 (d, J=2 Hz, C-S H), and 5.95 (d, C-2' Protons).

Example 62 Benzyl (3R,5R,Z)-2-[2-(α-chloroacet-B amido)ethylidene] clavam-3-carboxylate To a stirred solution of BAC (1.5 g) in ethyl acetate (30 ml) at 0 was added pyridine (1 ml) followed by chloroacetyl chloride (0.475 ml). After 10 mins the mixture was partitioned between ethyl acetate and 0.5 N HCI. The separated organic phase was washed successively with 0.5 N HCl, ol5 N aqueous NaHCO3 and water. The dried organic solution was evaporated and the residue chromatographed on silica gel to afford the title ester (0.55 g), #max (CHBr3) 1794 cm-1 (ss - lactam), # (CDCl3) 3.30 (broad, NH), 4.29 (dk J 3 Hz, C-5H), 5.99 (s, CH2Cl) and 6.03 (t, J 6 Hz, CH2NHCO).

Example 63 Sodium (3R,5R,Z)-2-[2-(α-chloroacet- amido)ethylidene]clavam-3-carboxylate A solutioon of benzyl (3R,5R,Z) - 2 - [2 (α - chloroacetamido) - ethylidene] clavam - 3 - carboxylate (0.43 g) in ethyl acetate (35 ml) -ethanol (70 ml) was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.26 g), [α]D20+33 (c0.7; H2O), #max(Nujol) 1778 cm-1 (ss - lactam), # (D2O) 4.27 (d, J 3 Hz, C-S H), 5.90 (s, CH2Cl) and 6.07 (d, J 7 Hz, CH2NHCO).

Example 64 Benzyl (3R,5R,Z)-2-[2-(a,a,a- trichloroacetamido)ethylidene]- clavam-3-carboxylate To a stirred solution of BAC (0.94 g) in ethyl acetate (100 ml) was added a solution of DCC (0.67 g) in ethyl acetate (50 ml) followed by a solution of trichloroacetic acid (0.53 g) in ethyl acetate (50 ml). After 45 mins the mixture was filtered and the filtrate washed successively with 0.5 N HCI, 0.5N HaHCO3 and water. The dried organic solution was evaporated and the residue chromatographed on silica gel to afford the title ester (0.54 g), #max (CHBr3) 1794 cm-1 (ss - lactam), # (CDCl3) 3.13 (broad, NH), 4.29 (d, J 3 Hz, C-S H) and 6.00 (t, J 6 Hz, CH2NHCO).

Example 65 Sodium (3R,5RZ)-2-[2-(α,α,α-trichloroacet- amido)ethylidene]-clavam-3-carboxylate A solution of benzyl (3R,5R,Z) 2 - [2 - (α,α,α - trichloroacetamido)ethylidene]clavam - 3 - carboxylate (0.43 g) in etyl acetate (35 ml) ethanol (70 ml) - was hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.11 g), #max (Nujol) 1782 cm-1 (ss lactam), # (D2O) 4.25 (C-5H) and 6.05 (d, J 6 Hz, CH2NHCO).

* Example 66 Benzyl (3R,5R,Z)-2-{2-[α-(methyltio) acetamido]ethylidene}-clavam-3-carboxylate A s u s p e n s i o n o f p o t a s s i u m (methylthio)acetate (0.158 g) in methylene chloride (10 ml) containing N,N - dimethylformamide (3 drops) at 0 was treated with a solution of oxalyl chloride (0.95 ml) in methylene chloride (5 ml) and was stirred for 1 hour. The resulting mixture was added slowly to a solution of BAC (0.3 g) and pyridine (0.16 ml) in ethyl acetate (20 ml) at 00. The mixture was stirred for 15 mins and then partitioned between 0.5 N HCI and ethyl acetate. The separated organic phase was washed successively with 0.5 N HCl, 0.5 N aqueous NaHCO3 and water. The dried organic solution was evaporated to afford an oil which solidified on trituration with ether. The solid was collected, washed and dried to give the title ester (0.26 g) p,,,, (CHBr3) 1794 cm (8 - lactam), T (CDCl2) 3.06 (broad, NH), 4.29 (d, J 3 Hz, C-S H), 6.03 (t, J 7 Jz, CH2NHCO), 6.83 (s, CH2SCH3) and 7.92 (s, SCH3).

Example 67 Sodium (3R,5R,Z)-2-{2-[α-(methyl- thio)acetamido]ethylidenelclavam-3 carboxylate A solution of benzyl (3R,5R,Z) - 2 - {2 - [α (methylthio)acetamido]ethylidene}clavam methylthio)acetamido]ethylidene}clavam 3 - carboxylate (0.28 g) in ethanol (50 ml) was hydrogenated for 45 mins at atmospheric pressure and ambient temperature over 10% palladium on carbon (1.47 g). The catalyst was removed by filtration through kieselguhr and the filtrate concentrated to ca 10 ml. The residue was stirred and treated with a solution of sodium 2 - ethylhexanoate (0.1 g) in ethyl acetate (5 ml) followed by an excess of ether. The resulting precipitate was collected, washed and dried to afford the title salt (0.115 g) [α]D20+27 (c 1.2; H2O), #max (Nujol) 1780 cm-1 (ss - lactam), # (D2O) 4.26 (d, J 3 Hz, C-S H), 6.10 (d, J 7 Hz, CH2NHCO), 6.80 (s, CH2SCH3) and 7.91 (s, CM2).

Example 68 Sodium (3 R,5R,Z)-2-(2-propionamido- ethylidene)clavam-3-carboxylate To a solution of BAC (0.5 g) in ethyl acetate (15 ml) was added DCC (0.36 g) in ethyl acetate (5 ml) followed by acrylic acid (0.13 ml) in ethyl acetate (5 ml). After 30 mins the mixture was filtered and the filtrate washed successively with 0.5 N HCI, 0.5 N aqueous NaHCO3 and water. The dried organic solution was evaporated and the residue chromotographed on silica gel to give benzyl (3R,5R,Z)- 2- (2 acrylamidoethylidene)clavam - 3 carboxylate (0.1 f g). This material was dissolved in ethanol (15 ml) and was then hydrogenated and worked up according to the method described in Example 41 to afford the title salt (0.03 g) #max (Nujol) 1780 cm-1 (ss - lactam) # (D2O) 4.26 (d, J 2 Hz, C-S H), 6.12 (d, J 7 Hz, CH2NHCO) 7.75 (q, J 8 Hz, CH2CH3) and 8.89 (t, J 8 Hz, CH2CH2).

Examples A-F In Examples A, B, D and E (3R,5R,Z) 2 - (2 - formamidoethylidene)clavam - 3 carboxylic acid is used as densified granules containing 1% w/w magnesium sterarate, which are prepared as follows: Blend (3R,5R,Z) - 2 - (2 formamidoethylidene)clavam - 3 carboxylic acid with 1% magnesium stearate and prepare tablet slugs by direct compression on a tablet machine. Break down the slugs through a series of screens (10, 12, 16 and 20 mesh) on a rotary granulator to produce free flowing densified granules with an apparent bulky density of about 0.7 g/ml (BSS method).

Amoxycillin trihydrate granules (used in Example B) and ampicillin trihydrate granules (used in Example E) may be prepared in similar manner.

Examples A and B Formula per tablet Example A mg Densified (3R,5R,Z)- 2 - (2 - (formamidoethylidene) clavam - 3 - carboxylic acid contianing 1% magnesium stearate 252.5 Empicol LZ ('Empicol' is a registered Trade Mark) 3.5 Explotab 7.0 Avicel pH 101 to tablet core weight of ('Avicel' is a registered Trade Mark) 350.0 Example B Densified (3R,5R,Z) - 2 (2 - formamidoethylidene) clavam - 3 - carboxylic acid containing 1% magnesium stearate 252.5 Densified amoxycillin trihydrate granules containing 1% magnesium stearate equal to 250 mg amoxycillin (approx.) 300.0 Explotab 12.5 Emcompress to tablet core weight of 650.0 Method of preparation Blend the granules with the rest of the excipients and compress the blend on a tablet machine using normal or deep concave punches of appropriate diameter (9-12 mm).

Example C Densify (3R,SR,Z) - 2 - (2 - formamidoethylidene)clavam - 3 - carboxylic acid by blending with approximately 2% starch paste and granulating. Then dry the granules and pass through a rotary granulator using 10, 12, 16 or 20 mesh sieve screens to produce free flowing densified granules.

Formula per tablet Densified (3R,5R,Z) - 2 (2 - formamidoethylidene) clavam - 3 - carboxylic acid containing approx. 2% starch paste (approx.) 255.0 Lactose 75.0 Explotab 7.5 Magnesium stearate 3.5 Starch maize (dried) to tablet core weight of 350.0 Method of preparation Blend the granules with the rest of the excipients and compress the blend on a tablet machine using normal or deep concave punches of appropriate diameter (9-12 mm).

Examples D and E Formula per capsule Example D Densified (3R,5R,Z) - 2 (2 - formamidoethylidene) clavam - 3 - carboxylic acid containing 1% magnesium stearate 252.5 Explotab 4.5 Aerosil 200 ('Aerosil is a registered Trade Mark) 2.0 Example E Densified (3R,SR,Z) - 2 (2-formamidoethylidene)- clavam - 3 - carboxylic acid containing 1% magnesium stearate 252.5 Densified ampicillin trihydrate granules containing 1% magnesium stearate equal to 250 mg ampicillin (approx.) 300.0 Explotab 10.0 Aerosil 200 5.0 Method of Preparation Blend the granules and excipients and fill the blend into size 2 (Example D) or size 0 (Example E) hard gelatin capsules (lock fitting type) on an automatic capsule-filling machine.

Example F Dry powder for injection Blend sterile sodium (3R,5R,Z) - 2 - (2 formamidoethylidene)clavam - 3 carboxylate (1 part) intimately under aseptic conditions with sterile cephazolin sodium (1 part). Fill the sterile blend aseptically into glass vials under a blanket of sterile nitrogen such that each vial contains 500 mg of each antibiotic. Close the vials using rubber discs or plugs held in position by aluminium sealing rings thereby preventing gaseous exchange or ingress of microorganisms.

Constitute the product by dissolving in Water for Injections shortly before administration. Other suitable sterile vehicles can be used in place of Water for Injections.

Empicol LZ is sodium lauryl sulphate available from Marchon Ltd.; Explotab is sodium starch glycolate available from Greeff Fine Chemicals Ltd. Croydon, Surrey, England; Avicel pH 101 is microcrystalline cellulose available from FMC Corporation, U.S.A.; and Emcompress is dicalcium phosphate dihydrate NF.

Claims (60)

1. WHAT WE CLAIM IS:1. Compounds of the formula (I)

   (wherein R is a mono-acylamino group or a cyclic diacylamino group, the acyl groups of which are linked to form with the nitrogen atom a heterocyclic ring, and R1 is a carboxyl or esterified carboxyl group) and salt forms thereof.
2. 2. Compounds as claimed in claim I wherein R represents a monoacylamino group.
3. 3. Compounds as claimed in claim I or claim 2 wherein R' represents an esterified carboxyl group derived from an aliphatic or araliphatic alcohol, a phenol or a stannanol.
4. 4. Compounds as claimed in claim 2 or claim 3 wherein R1 represents an esterified carboxyl group COOR7 wherein R7 represents a straight or branched substituted or unsubstituted alkyl or a alkenyl group having from 1--8 carbon atoms; an aralkyl group having up to 20 carbon atoms; an aryl group having up to 12 carbon atoms; or a cycloalkyl group having up to 12 carbon atoms, optionally containing one or more heteroatoms in the ring system, unsaturation optionally being present wnen one or more heteroatoms is present or stannyl group having up to 24 carbon atoms.
5. 5. Compounds as claimed in claim 4 whereinCOOR7 is a metabolically labjle ester group.
6. 6. Compounds as claimed in claim 4 wherein R7 is a diphenylmethyl group, a benzyl group or a benzyl group substituted by a nitro, methoxy or methyl group.
7. 7. Compounds as claimed in claim 4 wherein R is a benzyl group substituted by an o - nitro, p - methoxy or p - methyl group.
8. 8. Compounds as claimed in claim 4 wherein R7 is a p - nitrobenzyl group.
9. 9. Compounds as claimed in claim 4 wherein R7 represents a methyl or acetoxymethyl group.
10. 10. Compounds as claimed in any of claims 1--6, 8 and 9 wherein R represents a mono-acylamino group derived from a carboxylic or thiocarboxylic acid or a sulphonic acid.
11. Il. Compounds as claimed in claim 10 wherein R represents the grouping -NR2R2, wherein R2 represents a group -CYR4, -CY ZR6 or -CYNR4R5 in which Y and Z, which may be the same or different, are oxygen or sulphur, -SO2NR4R6 or -SO2R6, wherein R4 and R5, which may be the same or different, represent hydrogen or aliphatic, araliphatic, cycloaliphatic, aryl or C-attached heterocyclic groups or R5 together with R4 and the nitrogen atom to which they are attached form a heterocyclic ring, and R6 is as defined for R4 other than hydrogen, and R3 is a hydrogen atom.
12. 12. Compounds as claimed in claim 10 wherein R2 represents the grouping -NR2R2, wherein R2 represents a groupCYR4 or -CY ZR6 in which Y and Z are oxygen, R4 represents an aliphatic, araliphatic or aryl group, R6 is as defined for R4 other than hydrogen and R3 is a hydrogen atom.
13. 13. Compounds as claimed in claim 11 wherein R4, R5 and R6 each represent a straight or branched unsubstituted or substituted alkyl or alkenyl group having from 1=4 carbon atoms which group is optionally substituted by one or more halogen atoms or alkoxy, aryloxy, acyloxy, cyano, acyl, carboxyl, protected carboxyl, amino, protected amino, hydroxyl, protected hydroxyl, thiol, protected thiol or cycloalkadienyl groups; or an arylmethyl group having up to 10 carbon atoms, optional substituents on the methylene group of the aryl methyl group when the aryl group is phenyl being amino, carboxyl or hydroxy and protected forms thereof, optional substituents on the aryl group when the aryl group is a phenyl group being a p- hydroxy group and m sulphonamido group and when the aryl group is a heterocyclic aryl group, optional substituents being C14 alkyl groups; or an aryl group having up to 10 carbon atoms, such an aryl group being optionally substituted by a halogen atom or a cyano, alkoxy, or alkyl group; or a cycloalkyl group containing not more than 10 carbon atoms; or R4 and R6 together with the nitrogen atom to which they are attached, form a heterocyclic ring containing 5-7 ring members and optionally containing nitrogen, oxygen or sulphur as additional heteroatoms and carrying an alkyl group as optional substituent.
14. 14. Compounds as claimed in claim 12 wherein R4 and R6 each represent either a straight or branched unsubstituted or substituted alkyl or alkenyl group having from 1=4 carbon atoms which group is optionally substituted by one or more halogen atoms or a hydroxyl group; or an arylmethyl group having up to 10 carbon atoms; or an aryl group having up to 10 carbon atoms, such an aryl group being optionally substituted by a halogen atom or alkyl group.
15. 15. Compounds as claimed in claim 11 wherein where R is a group -CYR4, Y is a sulphur or oxygen atom and R4 is a hydrogen atom; a C14 alkyl group; a C14 alkyl group substituted by 1-3 halogen atoms, or a cyano, azido, hydroxyl, C14 alkoxy, C24 alkanoyloxy, C14 alkylthio (which may be substituted by 1-3 halogen atoms), phenoxy, amino, C14 alkanoylamino, protected amino, carboxyl or protected carboxyl group; a C24 alkenyl group; a benzyl group, a benzyl group substituted in the a - position by an azido, carboxyl, protected carboxyl, hydroxyl protected hydroxyl, amino or protected amino group and/or substituted in the phenyl ring by a hydroxyl group; a phenyl or pyridyl group; or a methyl group substituted by a carbon-attached 5-7 membered aromatic heterocyclic ring in which the heteroatoms are selected from nitrogen, oxygen and sulphur atoms or where R2 is group -CY. ZR6, Y and Z are oxygen atoms and R6 is a C14 alkyl benzyl group, or where R2 is a group -CYNR4R5, Y is oxygen or sulphur and one of R4 and R5 is a hydrogen atom, the other being a hydrogen atom br a C14 alkyl group, a phenyl group or a carbon-attached, saturated or unsaturated, 5-7 membered heterocyclic ring in which the heteroatoms are selected from oxygen, nitrogen and sulphur atoms, or where R2 is a group -SO2R6, R6 is a C14 alkyl group or a phenyl group or a phenyl group substituted by a methyl group, or where R2 is a group -SO2NR4R, and R4 and R5, which may be the same or different are hydrogen atoms or C14 alkyl groups.
16. 16. Compounds as claimed in claim 12 wherein where R is a group -CYR4, Y is oxygen; and R4 is a C14 alkyl group, optionally substituted by one or more halogen atoms or a hydroxyl group; a C24 alkenyl group; a benzyl group; or a phenyl group; or, where R2 is a group -CY ZR6, Y and Z are oxygen and R6 is a C14 alkyl or a benzyl group.
17. 17. Compounds as claimed in claim 16 wherein R4 is a C14 alkyl group substituted by 1-3 halogen atoms.
18. 18. Compounds as claimed in any of claims 1, 3-6, 8 and 9 wherein R represents a cyclic diacylamino group -NR2R3 where R2 and R3 together with the nitrogen atom to which they are attached form a heterocyclic group wherein the nitrogen atom is linked to a di - acyl group.
19. 19. Compounds as claimed in claim 18 wherein R2 and R3 form a ring having from .57 ring members optionally fused to a further ring.
20. 20. Compounds as claimed in claim 10 wherein R represents the grouping -NHCO . CONR4R5 or -NHCO.COR4 wherein R4 and R6 are as defined in claim 11.
21. 21. Compounds as claimed in claim I wherein R is an acetamido or benzamido group and R1 represents a carboxyl group or salts thereof.
22. 22. Compounds as claimed in claim 1 wherein R is a phenylureido, phenylthioureido or tosylamino group and R1 represents a carboxyl group or salts thereof.
23. 23. Compounds as claimed in claim 1 wherein R is a formamido group and R1 represents a carboxyl group or salts or esters thereof.
24. 24. Compounds as claimed in claim 1 wherein R is a methoxycarbonylamino, ethoxycarbonylamino or phthalimido group and R1 represents a carboxyl group or salts thereof.
25. 25. Compounds as claimed in claim 1 wherein R is a thiobenzamido, methylthioureido, ethylureido, (tetrahydropyran - 2 - yl)ureido or methanesulphonamido group and R represents a carboxyl group or salts thereof.
26. 26. Compounds as claimed in claim 1 wherein R is a cyanoacetamido, azidoacetamido, acetoxyacetamido, hydroxyacetamido, methoxyacetamido, (methylthio)acetamido, (trifluoromethyl ,thio)acetamido, phenoxy acetamido, aminoacetamido, benzyloxy carbonylaminoacetamido, N formylamino)acetamido, (N acetylamino)acetamido, 3 - (4 - methoxy benzyloxycarbonyl)propionylamino, 3 carboxypropionylamino, 3 - ethoxy propionylamino, 2 - azido - 2 phenylacetamido, 2 - amino - 2 phenylacetamido, 2 - hydroxy - 2 phenylacetamido, 2 - formyloxy - 2 phenylacetamido, 2 - (benzyloxy. carbonyl) - 2 - phenylacetamido, 2 - carboxy - 2 - phenylacetamido, 2 - (benzyloxy - carbonylamino) 2 - phenylacetamido, (4 - hydroxy phenyl) - acetamido, thien - 2 ylacetamido, thien - 3 - ylacetamido, fur 2 - ylacetamido, pyrid - 4 - ylacetamido, pyrid - 2 - ylcarbonylamino, pyrid - 3 ylcarbonylamino, pyrid - 4 yicarbonylamino, oxamido, phenylglyoxamido, ureido, methylureido, thien - 2 - ylureido, pyrid - 3 - ylureido, thioureido, phenylsulphonaimido, dimethylsulphamoylamino, or methylsulphamoylamino group, and R1 is a carboxyl group or salts thereof.
27. 27. Compounds as claimed in claim 1 wherein R is a bromoacetamido, chloroacetamido, dichloroacetamido, trifluoroacetamido, or trichloroacetamido group and R1 represents a carboxyl group or salts thereof.
28. 28. Compounds as claimed in claim I wherein R is a propionylamino, butyrylamino, isobutyrylamino, phenylacetamido, or maleimido group and R1 represents a carboxyl group or salts thereof.
29. 29. Compounds as claimed in claim I wherein R is a acryloylamino or succinimido group and R represents a carboxyl group or salts thereof.
30. 30. (3R,5R,Z) - 2 - (2 - Formamidoethylidene)clavam - 3 - carboxylic acid and salts thereof.
31. 31. (3R,5R,Z) - 2 - (2 Acetamidoethylidene)clavam - 3 carboxylic acid and salts thereof.
32. 32. (3R,5R,Z) - 2 - (2 Phenylureidoethylidene)clavam - 3 carboxylic acid and salts thereof.
33. 33. The alkali metal, alkaline earth metal, ammonium or organic base salts of compounds of formula (I) as claimed in any of claims 1, 2, 114, 16, 18, 19, 21-23, 28 and 3032.
34. 34. The alkali metal, alkaline earth metal, ammonium or organic base salts of compounds of formula (I) as claimed in any of claims 15, 17, 20, 24=27 and 29.
35. 35. The sodium, potassium lithium, calcium, magnesium or ammonium salt of a compound of formula (I) as claimed in any of claims 1, 2, 10=14, 16, 18, 19, 21-23, 28 and 30=32.
36. 36. The sodium potassium, lithium, calcium, magnesium or ammonium salt of a compound of formula (I) as claimed in any of claims 15, 17, 20, 24=27 and 29.
37. 37. The acid addition salts and zwitterionic forms of compounds as claimed in claim 1 in which R contains a basic group.
38. 38. A pharmaceutical composition (including a veterinary composition) comprising at least one acid of formula (I) as claimed in claim 1, or physiologically acceptable salt or metabolically labile ester thereof in admixture with a pharmaceutical carrier or excipient and/or a further p lactam antibiotic.

    '
39. 39. A composition as claimed in claim 38 wherein the further p - lactam antibiotic is a penicillin or cephalosporin.
40. 40. A composition as claimed in claim 38 or claim 39 wherein the further p-lactam antibiotic is cephalexin, cephaloglycin, ampicillin, amoxycillin, carbenicillin or ticarcillin or their orally absorbed esters; or cephalothin, cephaloridine, cefazolin, cephacetrile or cephapirin.
41. 41. A composition as claimed in any of claim 38=40 which is in the form of dosage units containing 12.5 mg to 5 g of active compound of formula (I) as claimed in claim 1 when this is employed alone and from 25 mg to 5 g of total p - lactam antibiotic when a compound of formula (I) as claimed in claim I and a further p - lactam antibiotic are present.
42. 42. A composition as claimed in any of claims 38-41 which contains the compound of formula (I) wherein R represents an acetamido phenylureido group and R1 represents a carboxyl group or salts thereof.
43. 43. A composition as claimed in any of claims 38-41 which contains the compound of formula' (I) wherein R represents a formamido group and R represents a carboxyl group or salts thereof.
44. 44. A process for the preparation of a compound of formula (I) as claimed in claim 1 which comprises reacting a compound of formula (I) wherein R is an -NH2 group with an acylating agent.
45. 45. A process as claimed in claim 44 wherein the acylating agent has the formula R2X wherein R2 is as defined in claim 11 and X is a displaceable substituent.
46. 46. A process as claimed in claim 45 wherein X represents a halogen atom, an O- acyl group, an O - hydrocarbyl group or a hydroxyl group.
47. 47. A process as claimed in any of claims 41 216 wherein the acylating agent is a carboxylic or thiocarboxylic acyl halide; a carbamoyl halide; a thiocarbamoyl halide; a sulponyl halide or haloformyl ester; a carboxylic or thiocarboxylic acyl anhydride; a carboxylic, thiocarboxylic or sulphonic acid in the presence of a coupling agent; an active ester of a carboxylic, thiocarboxylic or sulphonic acid; a ketene, sulphene, isocyanate, isothiocyanate or activated imide.
48. 48. A process as claimed in any of claims 44 to 47 wherein an activated derivative of the parent amine is formed prior to acylation.
49. 49. A process as claimed in any of claims 4448, wherein an acid product formed in the reaction is esterified to produce a compound of formula (I) in which R' is an esterified carboxyl group.
50. 50. A process as claimed in any of claims 44 to 48, wherein an ester product initially formed is subjected to deesterification followed by salt formation if desired.
51. 51. A process as claimed in claim 50 wherein the ester initially formed is an arylmethyl ester and deesterification is effected by catalytic reduction.
52. 52. A process as claimed in claim 50 wherein the ester initially formed is an arylmethyl ester and deesterification is effected by a dissolving metal reduction.
53. 53. A process as claimed in claim 47 wherein the activated imide has the formula R2R3N CYR8, wherein R2 and R3 together with the nitrogen atom to which they are attached, form a heterocyclic ring in which the nitrogen is linked to two carbonyl groups, Y represents oxygen or sulphur and R8 represents a group R4 or ZR6, where Z, R4 and R6 have the meanings given in claim 11.
54. 54. A process as claimed in any of claims 44 818 in which acylation is effected in the presence of a bistrialkyl tin oxide.
55. 55. A process as claimed in claim 44 wherein the compound of formula (I) initially produced contains a reducible atom or group and is subsequently subjected to reduction.
56. 56. A process as claimed in claim 44 wherein the compound of formula (I) initially produced contains in the group R a protected hydroxyl, thiol, amino or carboxyl group and is subsequently subjected to deprotection.
57. 57. A process as claimed in claim 44 substantially as hereinbefore described.
58. 58. A process as claimed in claim 44 substantially as described with reference to the Examples.
59. 59. A pharmaceutical composition as claimed in claim 38 substantially as hereinbefore described.
60. 60. A pharmaeutical composition as claimed in claim 38 substantially as hereinbefore described with reference to Examples A and B.