NO783132L - PROCEDURE FOR THE PREPARATION OF CLAVULANIC ACID AMINOETERS - Google Patents

Description

British Patent Applications Nos. 41897/75, 2629/76 and 19000/76

(see also Belgian patent no. 847045 and Japanese application no. 122725/76)

discloses, among other things, that ethers of clavulanic acid possess useful β-lactamase inhibitory properties which make them valuable as synergists for penicillins and cephalosporins. The useful properties of such compounds were again established in the later Japanese application No. 93792/77 (see also the later French application No. 2335222).

Further ethers of clavulanic acid have now been found which

gives good blood counts and urine recovery values after administration. These compounds are also more conveniently prepared than previously known nitrogen-substituted ethers.

The present invention provides compounds of formula (I):

and salts and esters thereof, where R"^" is a hydrogen atom or a methyl group; R 2 is a hydrogen atom or a methyl group; and R<3>is 4 4 4 5 4 a hydrogen atom or a COR -, CO2R - or CONR R - group where R is an alkyl group with up to 6 carbon atoms or a phenyl or benzyl group and R^ is a hydrogen atom or an alkyl group with up to 6 carbon atoms. 3 3 4 R is preferably a hydrogen atom. R is suitably a COR group. R<3> is suitably a C0~R 4 group. R<3> is suitably a 4 5

CONR R group.

Preferred values for the COR 4 group include acetyl, propionyl and benzoyl. Preferred values of the CC₂R₂ group include methoxycarbonyl, ethoxycarbonyl and benzyloxycarbonyl. Preferred values of the CONR 4 R 5 group include methylaminocarbonyl and dimethylaminocarbonyl.

12 . 12

CR R is preferably a CH0 share. CR R is fittingly a 12

CH(CH3) share. CR R is conveniently a C(CH 3 ) 2 ~ moiety.

One group of particularly preferred compounds according to the invention is that having formula (II):

12

where R and R are as defined with respect to formula (I).

The compounds of formula (II) normally exist in zwitterionic form.

A preferred compound according to the invention is 1 2

wherein R and R are each hydrogen atoms. This compound is thus 9-O-(2-aminoethyl)-clavulanic acid which is the compound of formula (III):

Since this compound normally exists in zwitterionic form, it can also be represented by formula (IV):

The zwitterionic compounds according to the invention are preferably provided in crystal form, as such crystal forms have improved storage possibilities. The compound is preferably practically pure, e.g. over 80%.

Other suitable compounds according to the invention include the compounds of formula (I) and salts thereof, wherein R 3 is

4 4 4 5

COR , C02R or CONR R as defined above. Particularly suitable compounds of this type are the pharmaceutically acceptable salts of

•these compounds.Suitable salts include alkali and alkaline earth metal salts, e.g. the sodium, potassium, calcium and magnesium salts. Other suitable salts include those of pharmaceutically acceptable nitrogen bases. The lithium and t-butylamine (NH.-,-C (CH^ ) ^ ) salts are also suitable. The preferred salts of such compounds include the sodium and potassium salts. 3 4 4 The compounds of formula (I) where R is COR , C0~R or CONR<4>R<5> can also be provided in the form of an ester. Such esters can be those which are cleavable by chemical methods, e.g. mild base hydrolysis or hydrogenolysis, or which are in vivo hydrolyzable. Suitable hydrolyzable esters include the methyl and methoxymethyl esters. Suitable hydrogenolizable esters include benzyl and substituted benzyl esters, e.g. p-methoxybenzyl, p-bromobenzyl, p-chlorobenzyl due to the p-nitrobenzyl esters. Suitable in vivo hydrolyzable esters include the acetoxymethyl, pivaloyloxymethyl, α-ethoxycarbonylethyl and phthalidyl esters.

The invention also provides a process for the preparation of the compounds of formula (i) or a salt or ester thereof, comprising reacting an ester of clavulanic acid with an aziridine derivative of formula (VI):

12 6

where R and R are as defined with respect to formula (I) and R is

4 4 4 5 4 5

a CO.R -, CO2R - or CO.NR R - group where R and R are as defined with respect to formula (I), and then, if desired, carrying out one or more of the following optional steps: (a) a compound of formula (I) or an ester thereof 3

wherein R is a benzyloxycarbonyl group, is subjected to hydrogenolysis to produce a compound of formula (I) wherein R 3 is a hydrogen atom;

(b) cleavage of the ester to form a salt or

an acid;

(c) esterification of the salt or acid produced in

the possible step (b).

The reaction between the ester of clavulanic acid and the aziridine normally takes place in an inert organic solvent, e.g. methylene chloride or the like, and normally at a reduced temperature, e.g. -30° to 5°C, and more commonly at approx. -20° to 0°C. However, the reaction may be allowed to gradually warm to ambient temperature to ensure that the reaction proceeds to completion. A catalyst, e.g. boron trifluoride etherate, is used.

The desired ether can be obtained from the reaction mixture by chromatography after washing the reaction mixture with sodium bicarbonate and/or water or brine.

The compounds of formula (I) where R 3 is a benzyloxycarbonyl group can be converted into a compound where R 3 is a hydrogen atom, by hydrogenation using an approximately atmospheric pressure of hydrogen and a catalyst, e.g. palladium, e.g. palladium on charcoal.

The esters of the compound of formula (I) can be converted into

the corresponding compound of formula (I) by hydrogenation or hydrolysis as described in Belgian patent document No. 847045. This Belgian patent also discloses suitable conditions for the esterification of the compounds of formula (i) or their salts.

In one preferred aspect, the invention provides a process for the preparation of esters of the compounds of formula (VII): wherein R 2 is as defined with respect to formula (VI), which comprises reacting an ester of clavulanic acid with a compound of formula (VIII) :

where R is as defined with respect to formula (VI).

A preferred method for the production of 9-0-(2-aminoethyl)-clavulanic acid comprises the hydrogenation of a compound of formula (IX): 1 2 .. ■ where C02A and C02A are groups which, by catalytic hydrogenation, are converted into C02H groups.

The above reaction proceeds via formation of a compound containing an 0-CH2-CH2-NH-CO2H moiety which then decarboxylates to produce the corresponding compound containing an 0-CH2-CH2-NH2~ group.

The catalyst used in the above reaction will normally be a noble metal catalyst and will usually be a palladium-based catalyst, e.g. palladium on carbon, palladium on barium sulphate or the like. A preferred catalyst is palladium on charcoal, e.g. 5, 10, 15 or 20% palladium on coal. The hydrogenation can use a lower, moderate or elevated hydrogen pressure, but it is convenient to use an approximate atmospheric pressure of hydrogen.

The reaction can be carried out at any convenient non-extreme temperature, e.g. 0-35°C, but in general it is preferred to use ambient temperature, e.g. 15-25°C.

The solvent used during the hydrogenation can be a conventional hydrogenation solvent, e.g. water together with acetone, ethanol, tetrahydrofuran or methanol or homogeneous mixtures of such solvents. A particularly suitable solvent is aqueous tetrahydrofuran.

1 2

In general, the groups A and A are benzyl or substituted benzyl groups, e.g. p-methoxybenzyl, p-bromobenzyl, p-chlorobenzyl, 1 2 p-nitrobenzyl or the like. The preferred groups A and A are benzyl groups.

As soon as the reaction is over, e.g. judged by thin-layer chromatography, the product can be obtained by filtering off solid materials and concentrating the solution until the product is obtained. If desired, the solution can be washed before or some time into the concentration process. Suitable concentration methods include freeze-drying and evaporation under reduced pressure. Trituration under ethanol can also be used.

The 9-O-(2-aminoethyl)-clavulanic acid can be obtained in crystal form by trituration under, or crystallization or recrystallization from, a suitable solvent, e.g. ethanol, possibly together with methanol or water. Ethanol is preferred for this purpose.

The compounds of formula (IX) can be prepared by reacting a corresponding ester of clavulanic acid with a compound of formula (X):

where A^" is- as defined with respect to formula (IX).

The condensation reaction can be carried out in an inert organic solvent, e.g. methylene chloride, at a first reduced temperature, e.g. -75 to 0°C, after which the reaction mixture can be gradually allowed to rise to room temperature. A catalyst, e.g. boron trifluoride etherate, is used. The desired compound can be obtained from the reaction mixture by chromatography after washing the reaction mixture with sodium bicarbonate solution and water or brine.

The present invention also provides a pharmaceutical preparation comprising a compound according to the invention and a pharmaceutically acceptable carrier for this.

The form of the preparations according to the invention may be similar to those described in the previously mentioned Belgian patent document No. 847045, which is hereby incorporated as a reference. As described in the aforementioned Belgian patent, preparations containing a compound according to the invention and a penicillin or cephalosporin are particularly suitable. A preferred penicillin for incorporation into such synergistic preparations is amoxycillin, e.g. amoxycillin sodium, amoxycillin potassium or amoxycillin trihydrate. Ampicillin is a further particularly suitable penicillin for use in such preparations.

A preferred preparation aspect according to the invention comprises 9-O-(2-aminoethyl)-clavulanic acid and a pharmaceutically acceptable carrier for this.

The preparations according to the invention include such

which has a form adapted for oral, topical or parenteral use and can be used for the treatment of infection in mammals, in-

clusive people.

Suitable forms of the preparations according to the invention include tablets, capsules, creams, syrups, suspensions, solutions, reconstitutable powders and sterile forms suitable for injection or infusion. Such preparations may contain conventional pharmaceutically acceptable materials, e.g. diluents, binders, coloring agents, flavoring agents, preservatives and disintegrants, in accordance with conventional pharmaceutical practice in the manner that is easily understood by the person skilled in the art when it comes to the composition of antibiotics. the preparations according to the invention can be formed by bringing the components together in a known manner, i.e. in current use or described in the literature.

Injectable or infusible preparations of the compound according to formula (III) are also very suitable, as particularly high tissue levels of the synergist can occur after administration by injection or infusion. Such preparations can essentially consist of the sterile compound, i.e. the compound itself without the addition of lubricants or the like. In accordance with conventional practice, such injectable preparations will be prepared in a sterile pyrogen-free liquid, e.g. water, for injection B.P.

Unit-dose preparations comprising compound (III) or a salt thereof adapted for oral administration constitute a further preferred preparation aspect according to the invention.

Under certain conditions, the effectiveness of oral preparations of compound (III) and its salts can be improved if such preparations contain a buffering agent or an enteric coating agent, so that the compounds according to the invention do not have prolonged contact with strongly acidic gastric juice. Such buffered or enteric-coated preparations may be prepared in accordance with conventional pharmaceutical practice.

The compound of formula (III) may be present in the preparation as a sole therapeutic agent or may be present together with an additional therapeutic agent, e.g. a penicillin or cephalosporin. Suitable penicillins and cephalosporins for* incorporation in such synergistic preparations include not only those known to be highly susceptible to β-lactamases, but also those which have a high degree of inherent resistance to some β-lactamases.

Naturally, if the penicillin or cephalosporin present in the synergistic preparations is not suitable for oral administration, then the preparation will be adapted for parenteral administration.

Penicillins suitable for incorporation into orally administrable compositions of the invention include benzylpenicillin, phenoxymethylpenicillin, propicillin, amoxycillin, ampicillin, epicillin, cyclacillin and other orally active penicillins and their pharmaceutically acceptable salts and in vivo hydrolyzable esters and aldehyde and ketone -adducts of the penicillins containing a 6-α-aminoacylamino side chain, and their pharmaceutically acceptable salts. Suitable penicillin in vivo hydrolyzable esters include the acetoxymethyl, pivaoyloxymethyl, α-ethoxycarbonyloxyethyl and phthalidyl esters of ampicillin or amoxycillin or phenyl -, tolyl and indanyl-α-esters of carbenicillin and ticarcillin and pharmaceutically acceptable salts thereof. Suitable aldehyde and ketone adducts of penicillins containing a 6-α-amirioacylamino side chain include the formaldehyde and acetone adducts of ampicillin and amoxycillin, e.g. metampicillin and hetacillin, and their salts. Suitable penicillins for incorporation into injectably or infusibly administrable preparations include the pharmaceutically acceptable salts of benzylpenicillin, phenoxymethylpenicillin, carbenicillin, propicillin, ampicillin, amoxycillin, epicillin, ticarcillin and cyclacillin.

Cephalosporins which are suitable for incorporation into orally administrable preparations according to the invention include cephalexin, cephradine, cephaloglycine and their pharmaceutically acceptable salts and other known cephalosporins and their pharmaceutically acceptable salts and in vivo hydrolyzable esters and aldehyde and ketone adducts of the cephalosporins containing a 7-a-aminoacylamino side chain, and their pharmaceutically acceptable salts. Suitable cephalosporins for incorporation into the injectable or infusible preparations according to the invention include the pharmaceutically acceptable salts of cephaloridine, cephalothin, cefazolin, cephalexin, cefa-cetril, cefamandole , cefapirin, cephradine, cephaloglycin and other known cephalosporins.

When present in a pharmaceutical preparation together with a penicillin or cephalosporin, the weight ratio between the compound of formula (III) and the penicillin or cephalosporin can be from e.g. 10:1 to 1:10, e.g. 3:1 to 1:3.

Preparations according to the invention can be used for the treatment of infections in, among other things, the respiratory tract, urinary

the roads and the soft tissue in humans.

Preparations according to the invention can also be used for the treatment of infections in livestock, e.g. in mastitis in cattle. thus, the invention provides a method for treating bacterial infections in mammals, i.e. not in humans, which includes the administration of a preparation according to the invention. This method is most suitable for treating mastitis in cattle.

The penicillin or cephalosporin in a synergistic preparation according to the invention will normally be present in approximately the amount that is conventionally used when the penicillin or cephalosporin is the "only therapeutic agent used in the treatment of the infection."

The weight of the compound of formula (III) in a unit dosage form according to the invention will suitably be from 50 to 500 mg and

more suitably from 50 to 250 mg.

In general, the total amount of antibacterial agents present in a synergistic preparation according to the invention will not be greater than 1500 mg and will usually be between 100 and 1000 mg. . Normally, between 500 and 3000 mg of the synergistic preparations according to the invention will be administered each treatment day (to an average adult person of 70 kg). However, for the treatment of severe systemic infections or infections in particularly intransigent organisms, higher doses may be used in accordance with clinical practice.

For the treatment of infections, the synergistic preparations according to the invention are normally adapted to produce a blood level peak of at least 0.1 µg/ml, more suitably at least 0.25 µg/ml, and preferably at least 1 µg/ml of the compound of formula ( III).

Particularly preferred preparations according to the invention will contain 150-1000 mg of amoxycillin, ampicillin or an in vivo-hydrolyzable ester or an aldehyde or ketone adduct thereof or a pharmaceutically acceptable salt thereof, and 50-500 mg of the compound of formula (III) , and a pharmaceutically acceptable carrier therefor.

More suitably, the preparations will contain 200-500 mg of amoxycillin or a salt thereof or ampicillin or a salt thereof. More suitably, the preparations will contain 50-250mg of the compound of formula (III).

Most suitably, the preparations will contain the compound of

formula (III) in crystal form.

The materials present in such preparations can

be hydrated. Thus, the ampicillin may be present as ampicillin trihydrate, and the amoxycillin may be present as amoxycillin trihydrate.

The weight amounts of antibiotics in such preparations are expressed

on the basis of pure free antibiotic equivalent present and not on the basis of salt, ester, adduct or hydrate.

The other compounds according to the invention can also be used in preparations as described for 9-O-(2-aminoethyl)-clavulanic acid.

The preparations according to the invention are preferably prepared in dry conditions.

The following examples illustrate the invention.

Example 1

Benzyl-9-O-(2-benzyloxycarbonylaminoethyl)-clavulanate

A stirred solution of 1.156 g of benzylclavulanate and 1.0 g of 1-benzyloxycarbonylaziridine in 20 ml of dry methylene chloride was cooled in a dry ice/acetone bath. To this was added 0.04 ml of boron trifluoride etherate, and the mixture was allowed to warm to room temperature for 3 hours. Excess sodium bicarbonate solution was added to the mixture and the organic phase was separated. the aqueous phase was extracted with chloroform, and the combined organic solutions were washed with brine, dried over magnesium sulfate and evaporated. the products were separated by column chromatography (silica gel, gradient elution 1:2 ethyl acetate:cyclohexane transitioning to 1:1 ethyl acetate:cyclohexane). The fractions containing the desired product (identified by t.l.c.) were evaporated to give benzyl-9-O-(2-benzyloxycarbonylaminoethyl)-clavulanate (727 mg):

I.R.Vmax (film) NOK 3,370 1805, 1750 and 1710 (wide) cm"<1>.

N.M.R. 5 (CDCl3), 2/94 (1H, d,J=17Hz), 3.2-3.5 (5H, m), 3.98 (2H,

d, J=7Hz), 4.71 (lH, broad t,J=7Jz), 4.9-5.3 (6H, two prominent singlets at 5.02 and 5.11), 5.57 (lH, d, J-3Hz), 7.26 (10H, s).

Recrystallization from ethyl acetate/cyclohexane gave the title compound as a white solid, m.p. 62-63°C;

Analysis: Found C,64.02; H, 5.62; N,6.20jRequires C,64.37; H,5,62, N,6,01, I.R.V v (nujol) 3320, 1804, 1738, 1688 cm"<1>.

Example 2

9- O-(2-aminoethyl)-clavulanic acid

A solution of 125 mg of benzyl-9-O-(2-benzyloxycarbonyl-aminoethyl)-clavulanate in 5 ml of tetrahydrofuran and 2.5 ml of water was hydrogenated over 10% palladium/charcoal (40 mg) for 1/2 hour. The solution was filtered through "Celite" and the filter cake washed with aqueous tetrahydrofuran. The combined filtrates were evaporated on the rotary evaporator until most of the tetrahydrofuran was removed. The aqueous solution was extracted three times with ethyl acetate, filtered through "Celite" and freeze-dried to give 9-O-(2-aminoethyl)-clavulanic acid (35 mg) as a solid.

I.R.V mak, s (KBr) 1780, 1690 .and 1610 cm<-1>,

N.M.R. 6 (D20) 2.95-3.25 (3H, m), 3.4-3.75 (3H, m) 4.14 (2H, d, J=7Hz), 4.85 (lH, wide t ,J=7Hz), 4.93 (1H, s), 5.68 (1H, d,J=3Hz).

Example 3

9- O-(2-aminoethyl)-clavulanic acid

A solution of benzyl-.9-0-(2-benzyloxycarbonylaminoethyl)-clavulanate in 40 ml of tetrahydrofuran and 20 ml of water was hydrogenated over 10% palladium/charcoal (800 mg) for 1/2 hour. The solution was filtered through "Celite" and the filter cake washed with water. The combined filtrates were evaporated on a rotary evaporator to remove most of the tetrahydrofuran. the aqueous solution was extracted three times with ethyl acetate and concentrated to a small volume (about 1 ml) on a rotary evaporator. Absolute ethanol was then added and the mixture again evaporated to a small volume. More ethanol was then added and the gummy precipitate scraped to induce crystallization. More ethanol was slowly added to complete deposition of the product. The 9-O-(2-aminoethyl)-clavulanic acid was filtered off and obtained as very pale yellow small prisms (362 mg) and dried in vacuo over P 2 O 2 . I.R. V IXlci, KS . (KBr) 3410 (wide) 1790, 1691, 1610(wide), 1383, 1308, 1190, 1152, 1090, 1040, 1019, 893, 748.

N.M.R. 6 (D20) 1.13 (~1.3H, t,J=7.5Hz), 2.95-3.2 (3H, m), 3.4-3.75 (~-3.8 H, m), 4.12 (2H, d,J=7Hz), 4.86 (lH, wide t,J=7Hz), 4.92 (lH, s) 5.69 (lH, d,J=3Hz) .

(The triplet at Sl.13 is due to the CH^ protons in ethanol, and part of the multiplet at 3.4-3.75 is due to the CH2~ protons in ethanol).

Example 4

Benzyl-9-O-(2-benzyloxycarbonylamino-1,1-dimethylethyl)-clavulanate

A stirred solution of 1.156 g of benzylclavulanate and 1 g of N-benzyloxycarbonyl-2,2-dimethylaziridine in 20 ml of dry methylene chloride was cooled in a dry ice/acetone bath and treated with 0.04 ml of boron trifluoride etherate. The mixture was then allowed to warm to room temperature in 6 hours. Excess sodium bicarbonate solution was then added and the organic phase separated and the aqueous phase extracted twice with chloroform. The combined extracts were washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, gradient elution 3:1 cyclohexane:ethyl acetate transitioning to 1:1 cyclohexane:ethyl acetate). Evaporation of the solvent gave benzyl 9-O-(2-benzyloxycarbonylamino-1,1-dimethylethyl)-clavulanate (330 mg)

in the form of an oil.

I.R.Vmax (film) 3400, 1805, 1745, 1725 cm<-1>.

N.M.R. <S(CDCl 3 ) 1.12 (6H, s,), 2.92 (1H, d, J«17Hz), 3.1-3.4 (3H, m) , 3.8-3.95 (2H , m), 4.69 (lH, wide t,J=7Hz) 4.99 (lH, s), 5.03

(2H, s), 5.10 (2H, s), 4.9-5.3 (lH, wide, s), 5.55 (lH, d,J=3Hz), 7.2 5 (10H, s).

Example 5

9-O-(2-amino-1,1-dimethylethyl)-clavulanic acid

A solution of 330 mg of benzyl-9-O-(2-benzyloxycarbonylamino-1,1-dimethylethyl)-clavulanate in 10 ml of tetrahydrofuran and 5 ml of water was hydrogenated over 10% palladium/charcoal (100 mg) for 1 hour. The solution was filtered through "Celite" and the filter cake washed with water. The combined filtrates were evaporated on a rotary evaporator to remove most of the tetrahydrofuran, and the aqueous solution was extracted three times with ethyl acetate and freeze-dried to give 153 mg of 9-O-(2-amino-1,1 -dimethylethyl)-clavulanic acid in the form of a solid.

I.R. vmax (KBr) 1780, 1692 and 1600 cm"<1>.

N.M.R. 6(D20) 1/23 (6H, s), 2.97 (2H,s), 3.02 (lH, d,J=17Hz), 3.50 (lH, dd, J=3 and 17Hz), 4.01 (2H, d,J_=7Hz), 4.81 (lH, wide t, J=7Hz) , 4.87 (1H, wide s), 5.63 (lH, d,J=3Hz).

Example 6

Benzyl-9-O-(2-benzamidoethyl)-clavulanate

A stirred solution of 289 mg of benzylclavulanate and 150 mg of N-benzoylaziridine in 5 ml of dry methylene chloride was cooled in a dry ice/acetone bath and treated with 0.01 ml of boron trifluoride etherate. After 1 hour the mixture was allowed to warm to room temperature and a further portion of boron trifluoride etherate (0.02 ml) was added. The mixture was stirred at room temperature for 4 hours and then treated with excess sodium bicarbonate solution. The organic phase was separated and the aqueous phase extracted twice with chloroform. The combined extracts were washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, gradient elution 2:1 cyclohexane:ethyl acetate transitioning to 1:1 cyclohexane:ethyl acetate). by evaporation of the solvent, 230 mg of benzyl-9-0-(2-benzamido-ethyl)-clavulanate was obtained in the form of a oil. I.R.Ymaks (film)3350, 1805, 1750, 1695 and 1650 cm<-1>.

N.M.R. 6(CDCl3) 2.95 (1H, d, J=17Hz), 3.25-3.7 (5H, m), 4.04 (2H, d, J=17Hz), 4.74 (1H, broad t, J=7Hz), 5.01.(lH, wide s,), 5.12 (2H, s), 5.58 (lH-, d,J=3Hz), 6.50 (lH, wide s ,), 7.15-7.45 (8H, m), 7.6-7.8 (2H, m).

Example 7

Sodium 9-O-(2-benzamidoethyl)-clavulanate

A solution of 224 mg of benzyl-9-O-(2-benzamidoethyl)-clavulanate in 5 ml of tetrahydrofuran was hydrogenated over 10% palladium/charcoal (70 mg) for 1/2 hour. The solution was filtered through "Celite" and the filter cake washed with tetrahydrofuran. The solution was diluted with 5 ml of water and then treated with a solution of 43 mg of sodium bicarbonate in 3 ml of water. Most of the tetrahydrofuran was removed on a rotary evaporator, and the aqueous solution was extracted three times with ethyl acetate. The solution was filtered through "Celite" and freeze-dried to give solid sodium 9-O-(2-benzamidoethyl)-clavulanate (123 mg).

I.R.Vmax (KBr)1780, 1690 and 1620 (broad) cm<-1>.

N.M.R. 6 (D20) 2.89 (lH, d, J=18Hz), 3.25-3.7 (5H, m), 4.08 (2H,

d,J=8Hz), 4.84 (lH, wide t, j=8Hz), 4.84 (lH, s), 5.59 (lH, d, J=3Hz), 7.3-7.8 (5H, m).

Example 8

Benzyl-9-O-(2-benzamido-1,1-dimethylethyl)-clavulanate

A stirred solution of 289 mg of benzylclavulanate and 200 mg of N-benzoyl-2,2-dimethylaziridine in 5 ml of dry methylene chloride was cooled in an ice bath and treated with 0.02 ml of boron trifluoride etherate. After 1 hour, the mixture was allowed to warm to room temperature over 2 hours. Excess sodium bicarbonate solution was then added and the organic phase separated. The aqueous phase was extracted twice with chloroform and the combined organic extracts washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, gradient elution 2:1 cyclohexane:ethyl acetate passing to 1:1 cyclohexane:ethyl acetate. Evaporation of the solvent gave benzyl 9-O-(2-bénzamido-1,1-dimethylethyl)-clavulanate ( 104 mg) in the form of an oil. I.R.V max (film) 3400, 1805, 1750, 1700 and 1660 cm"<1>.

N.M.R. 6 (CDCl3) 1.22 (6H, s), 2.86 (1H, d,J=17Hz), 3.2-3.55 (3H, m), 3.96 (2H, d,J=7Hz ) 4.77 (lH, wide t, J=7Hz), 5.03 (lH, s), 5.12 (2H, s) 5.4 (lH, d,J=3Hz), 6.47 (lH , wide s), 7.2-7.45 (8H, m) 7.6-7.75 (2H, m).

Example' 9

Sodium 9-O-(2-benzamido-1,1-dimethylethyl)-clavulanate

A solution of 104 mg of benzyl-9-O-(2-benzamido-1,1-dimethyl-ethyl)-clavulanate in 5 ml of tetrahydrofuran was hydrogenated over 10% palladium/charcoal (30 mg) for 20 min. The solution was filtered through "Celite" and the filter cake washed with tetrahydrofuran. The combined filtrates were treated with a solution of 18.8 mg of sodium bicarbonate in water and then most of the tetrahydrofuran was removed on a rotary evaporator. The aqueous solution was extracted twice with ethyl acetate and evaporated on a rotary evaporator. The evaporation residue was dried under vacuum over phosphorus pentoxide to give dry sodium 9-O-(2-benzamido-1,1-dimethylethyl)-clavulanate (74 mg) in the form of a solid.

I.R.V max. (KBr) 1785, 1692 and 1625 (broad) cm<-1>.

N.M.R. 6(D20), 1.17 (6H, s), 2.77 (lH, d, J=17Hz), 3.34 (lH, dd, J=3 and 17Hz), 3.38 (2H, s) , 4.00 (2H, d, J=8Hz), 4.84 (lH, wide t, J=8Hz), 4.85 (lH, s) 5.54 (lH, d,J=3Hz), 7 .3-7.8 (5H, m).

Example 10

Benzyl-9-O-[2-(N-cyclohexyl-ureido)-ethyl]-clavulanate

A stirred solution of 289 mg of benzylclavulanate and 200 mg of 1-(N-cyclohexyl)carboxamido-aziridine in 5 ml of dry methylene chloride was cooled in an ice bath and treated with 0.01 ml of boron trifluoride

ethereal. After 1 hour, the mixture was allowed to warm to room temperature for 3 hours. Excess sodium bicarbonate solution was then added, the organic phase was separated and the aqueous phase was extracted twice with chloroform. The combined organic phases were washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, gradient solution 1:1 ethyl acetate:cyclohexane increasing to 100% ethyl acetate). Recrystallization from ethyl acetate gave benzyl 9-O-[2-(N-cyclohexyl)-ureido-ethyl]-clavulanate (43 mg), m.p. 153-155°C. I.R.V max. (nujol) 3350, 1805, 1742, 1695, 1630 cm<-1>.

N.M.R. 6 (CDCl3), 0.8-2.1 (10H, m), 3.0 (1H, d,J=17Hz), 3.15-3.60

(6H, m), 4.02 (2H, d,J=7Hz), 4.45-4.85 (3H, m), 5.04 (lH,s), 5.15 (2H, s) 5 .63 (1H, d,J=3Hz), 7.28 (5H, s).

Found C, 62.76; H, 6.54; N, 8.9<0;><c>24H3lN3°6' requires c'63.00; H, 6.83; N,.9,18.

Example 11

Sodium 9-O-[2-N-cyclohexyl-ureido)-ethyl]-clavulanate

A solution of 247 mg of benzyl-9-0-[(N-cyclohexylureido)-ethyl]-clavulanate in 10 ml of tetrahydrofuran was hydrogenated over 10% palladium/charcoal (80 mg) for 20 min. The solution was filtered through "Celite" and the filter cake washed with tetrahydrofuran. The combined filtrates were treated with a solution of 45.4 mg sodium bicarbonate in water and the tetrahydrofuran removed on a rotary evaporator. The aqueous solution was extracted twice with ethyl acetate, filtered through "Celite" and evaporated on a rotary evaporator. The evaporation residue was dried over phosphorus pentoxide to give sodium 9-0-[2-(N-cyclohexyl-ureido)- ethyl]-clavulanate (170 mg).

I.R.Vmax. (KBr) 1770, 1695 and 1600 (very broad) cm"<1>.

N.M.R. 6 (D20) 0.8-2.0 (10H, m), 3.05 (lH, d,J=17Hz), 3.1-3.7 (6H,

m), 4.09 (2H, d,J=8Hz), 4.86 (lH, wide t,J=8Hz), 4.92 (lH, s), ■ 5.70 (lH, d, J= 3Hz).

Example 12

Benzyl-9-O-[2-(N-propyl-ureido)-ethyl]-clavulanate

A stirred solution of 289 mg of benzylclavulanate and 200 mg of 1-(N-propyl-carboxamido)-aziridine in 5 ml of dry methylene chloride was cooled in an ice bath and treated with 0.05 ml of boron trifluoride etherate which was added over 10 min. The mixture was then allowed to warm to room temperature for 2 hours. Excess sodium bicarbonate solution was then added and the organic phase separated. the aqueous phase was extracted twice with chloroform, and the combined organic phases were washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, gradient elution 1:1 ethyl acetate:cyclohexane which changed to 100% ethyl acetate), and by evaporation of the solvent benzyl-9-0-[2-(N-propyl-ureido)-ethyl] -clavulanate (23 mg). I.R.V max. (nujol) 3330, 1800, 1740, 1690 and 1615 cm-1.

N.M.R. MCDCl3) 0.89 (3H, t, J=7Hz), 1.48 (2H, sextet, J=7Hz), 2.85-3.60 (8H, m) 4.Ol (2H, d,J= 7Hz), 4.75 (lH, wide t,J=7Hz), 4.50-5.0 (2H, wide), 5.04 (lH, s), 5.15 (2H,s), 5, 63 (1H, d, J=3Hz), 7.28 (5H, s).

Example' 13

Methoxymethyl-9-O-(2-benzyloxycarbonylaminoethyl)-clavulanate

A stirred solution of 486 mg of methoxymethylclavulanate and

500 mg of 1-benzyloxycarbonylaziridine in 10 ml of dry methylene chloride was cooled in a dry ice/acetone bath and treated with 0.02 ml of boron trifluoride etherate. After 1 hour, a further portion of boron trifluoride etherate (0.02 ml) was added. After 1 more hour, the mixture was allowed to warm to room temperature and then shaken with excess sodium bicarbonate solution. The organic phase was separated and the aqueous phase extracted twice with chloroform. The combined extracts were washed with brine, dried over magnesium sulfate and evaporated. the product was isolated by column chromatography (silica gel, 1:1 ethyl acetate:cyclohexane as eluent. Evaporation of the solvent gave methoxymethyl-9-0-(2-benzyloxy-carbonylaminoethyl)-clavulanate (212 mg) in the form of an oil. I.R.V max. ( film) 3460, 1805, 1750, 1720 and 1625 cm<-1>.

N.M.R. fc(CDCl3) 3.00 (1H, d,J=17Hz), 3.2-3.6 (8H, m), 4.03 (2H,

d,J=7Hz), 4.81 (lH, wide t,J=7Hz), 4.9-5.4 (lH, wide s), 5.64 (lH, d,J=3Hz), 7, 27 (5H, p).

Example 14

Lithium-9-O-(2-benzyloxycarbonylaminoethyl)-clavulanate

A solution of 181 mg of methoxymethyl-9-0-(2<1->benzyloxycarbonylamino)-ethylclavulanate in 20 ml of tetrahydrofuran and 20 ml of water was hydrolyzed with lithium hydroxide on a pH-stat at pH 9. After 48 minutes the tetrahydrofuran was removed on a rotary evaporated and the aqueous solution extracted three times with ethyl acetate. The solution was evaporated on a rotary evaporator and the evaporation residue dried over phosphorus pentoxide so that 102 mg of lithium 9-0-(2-benzyloxycarbonylaminoethyl)-clavulanate was obtained as a solid.

I.R. V max. (KBr) 1775, 1685 and 1610 cm"<1>.

N.M.R. b(D2O) 2.91 (lH, d,J=17Hz), 3.1-3.55 (5H, m), 4.00 (2H,

d, J=7Hz), 4.79 (lH, wide,J=7Hz), 4.87 (lH, s), 4.98 (2H, s), 5.61 (lH, d,J=3Hz) , 7.2 9 (5H, p).

Example 15

Methoxymethyl-9-0-[2-(N-cyclohexyl-ureido)-ethyl]-clavulanate

To a stirred solution of 486 mg of methoxymethylclavulanate

in 2 ml of dry methylene chloride at 0°C there were, independently of each other,

added one solution of 400 mg of 1-(N-cyclohexylcarboxamido)-aziridine in 4 ml of methylene chloride and 0.12 ml of boron trifluoride etherate at the same proportional rate during 20 min. After an additional 1/2 hour at 0°C, the mixture was allowed to warm to room temperature and was then treated with excess sodium bicarbonate solution. The organic phase was separated and the aqueous phase extracted with 2 portions of chloroform. The combined organic phases were washed with salt water, dried over magnesium sulfate and evaporated. The evaporation residue was triturated with ether and allowed to stand at 5°C overnight. The supernatant was removed and the gummy solid washed with fresh ether and then with 1:1 ether:ethyl acetate. The resulting solid was recrystallized from ethyl acetate to give 43 mg of methoxymethyl-9-O-[2-(N-cyclohexyl-ureido)-ethyl]-clavulanate. I.R.V max. (nujol) 3320, 1805, 1745, 1693 cm"<1>.

N.M.R. 6(CDC13) 0.8-2.0 (10H, m), 3.00 (1H, d,J=17Hz), 3.1-3.6

(6H, m), 3.40 (3H, s), 4.01 (2H, d, J=7Hz), 4.79 (lH, wide t, J=7Hz), 4.6-5.1 ( 2H, wide), 5.01 (lH, s), 5.18 (1H, d,J=6Hz), .5.28 (lH, d,J=6Hz), 5.62 (1H, d,J =3Hz).

Analysis. Found: C, 55.46; H, 7.10; N, 10.2<1;><C>19H29<N>3°7 Required:.C, 55.46; H, 7.10; N, 10,21.

Example 16

Methoxymethyl- 9- O-( 2- N, N- dimethylureidoethyl)- clavulanate

To a stirred solution of 486 mg of methoxymethylclavulanate

1 2 ml of methylene chloride, cooled in an ice bath, were added independently, but at proportionally the same rate, 0.12 ml of boron trifluoride etherate and a solution of 400 mg of 1-(N,N-dimethylcarboxamido)- aziridine in 4 ml methylene chloride over 20 min. The mixture was stirred at 0° for 1 1/2 hours and then treated with excess sodium bicarbonate solution. The organic phase was separated and the aqueous phase extracted twice with chloroform. The combined organic phases were washed with brine, dried over magnesium sulfate and evaporated. the product was isolated by column chromatography (silica gel, ethyl acetate as eluent). Yield: 2 29 mg. I.R.Vmax. (film) 3380, 1805, 1755, 1695 and 1640 cm<-1>.

N.M.R. & (CDCl3) 2.86 (6H, s), 3.04 (1H, d, J=17Hz), 3.3-3.65 (8H, m), 4.07 (2H, d, J=7Hz ), 4.8 (lH, wide s), 4.84 (lH, wide t, J=7Hz), 5.05 (lH', s), 5.22 (lH, d, J=6Hz), 5 .31 (lH, d, J=6Hz), 5.66 (lH, d,J=3Hz).

Example 17

Lithium- 9- O-( 2- N', N'- dimethylureidoethyl)- clavulanate

A solution of 223 mg of methoxymethyl-9-0-(2-N<1>,N<1->dimethyl-ureidoethyl)-clavulanate in 5 ml of tetrahydrofuran was hydrolyzed in an aqueous solution of lithium hydroxide on a pH-stat at pH 9. When the hydrolysis was complete, the tetrahydrofuran was removed on a rotary evaporator, and the aqueous solution was extracted twice with ethyl acetate. The solution was then evaporated and the evaporation residue dried over phosphorus pentoxide. Yield = 126 mg.

I.R.Vmax. (KBr) 1780, 1690 and 1620 cm-1.

N.M.R.6 (D20) 2.80 (6H, s), 3.03 (lH, d, J=17Hz), 3.15-3.65 (5H, m), 4.06 (2H, d, J= 7Hz), 4.84 (lH, wide t, J=7Hz), 4.89 (lH, s), 5.67 (lH, d, J=3Hz).

Example 18

Methyl-9-O-[2-benzamido-1,1-dimethylethyl]-clavulanate

A stirred solution of 213 mg of methylclavulanate and 175 mg of N-benzoyl-2,2-dimethylaziridine in 5 ml of methylene chloride was ice-cooled in an ice bath and treated with 0.02 ml of boron trifluoride etherate. After 2 hours at 0 C, the mixture was allowed to warm to room temperature for 1 hour. Excess sodium bicarbonate solution was then added and the organic phase separated. The aqueous phase was extracted twice with chloroform and the combined organic phases washed with brine, dried over magnesium sulfate and evaporated. the product was isolated by column chromatography of the residue (silica gel, 1:1 ethyl acetate: cyclohexane switching to pure ethyl acetate as eluent). Yield 102 mg.I.R.Vmax. (film) 3350, 1802, 1752, 1695, 1655 cm""<1>.

N.M.R. & (CDCl3) 1.25 (6H, s), 2.89 (lH, d,J=17Hz), 3.39 (lH, dd,J=3 and 17Hz), 3.45 (2H, d, J =7Hz), 3.73 (3H, s), 4.07 (2H, d, J=7Hz), 4.82 (lH, wide t, J=7Hz) 5.02 (lH, wide s), 5 .58 (lH, d, J=3Hz), 6.55. (lH, wide s), 7.2-7.8 (5H. m) .

Example 19

Methyl-9-O-(2-benzyloxycarbonylaminoethyl)-clavulanate

A stirred solution of 852 mg of methylclavulanate and 1 g of N-benzyloxycarbonylaziridine in 20 ml of methylene chloride was cooled in a dry ice/acetone bath and treated with 0.04 ml of boron trifluoride etherate. The mixture was then allowed to warm to room temperature for 3 hours. Excess sodium bicarbonate solution was then added and the organic phase separated. The aqueous phase was extracted twice with chloroform and the combined organic phases washed with brine, dried over magnesium sulfate and evaporated. The product -was isolated by column chromatography (silica gel, 2:1 cyclohexane:ethyl acetate changing to 1:1 cyclohexane:ethyl acetate, as eluent. Yield = 543 mg. I.R.Vmax. (film) 3340, 1805, 1755, 1725, 1715 cm <-1>. N.M.R. 8(CDCl3) 2.99 (1H, d,J=17Hz), 3.25-3.55 (5H, m), 3.73 (3H, s), 4.03 (2H , d,J=7Hz), 4.78 (lH, wide t,J=7Hz), 5.02 (lH, wide s), 5.05 (2H, s), 5.0-5.2 (lH , wide s), 5.62 (lH, d, J=3Hz), 7.27 (5H, s) .

Example 20

Benzyl-9-O-(2-acetamido-1,1-dimethylethyl)-clavulanate

A stirred solution of 578 mg of benzylclavulanate and 250 mg of N-acetyl-2,2-dimethylaziridine in 10 ml of methylene chloride was cooled in a dry ice/acetone bath and treated with 0.04 ml of boron trifluoride etherate. After 1 hour, the mixture was allowed to warm to room temperature for 2 hours. The mixture was then treated with an excess of sodium bicarbonate solution. The organic phase was separated and the aqueous phase extracted twice with chloroform. The combined organic solutions were washed with brine, dried over magnesium sulfate and evaporated. The product was isolated by column chromatography (silica gel, 2:1 cyclohexane:ethyl acetate converting to 1:1 cyclohexane:ethyl acetate. Yield =. 272 mg. I.R.Vmax. (film) 3320, 1810, 1750, 1665 cm"<1>.

N.M.R. MCDC13), 1.15 (6H, s), 1.95 (3H, s), 3.0 (1H, d,J=17Hz), 3.23 (2H, d,J=6Hz), 3.46 (lH, dd, J=3 ogl7Hz), 3.95 (2H, m), 4.74 (lH, wide t,J=7Hz), 5.05 (lH, s) 5.15 (2H,s) , 5.64 (lH, d, J=3Hz), 5.8 (1H, very broad, s), 7.29 (5H, s).

Example 21

Benzyl-9-O-(2-acetamidoethyl)-clavulanate

A stirred solution of 1.156 g of benzylclavulanate and 500 mg of N-acetylaziridine in 20 ml of dry methylene chloride was cooled in a dry ice/acetone bath and treated with 0.08 ml of boron trifluoride etherate. The mixture was then allowed to warm to room temperature for 3 hours. Excess sodium bicarbonate solution was then added and the organic phase was separated. The aqueous phase was extracted twice with methylene chloride, and the combined organic phases were washed with brine, dried over magnesium sulfate and evaporated. the product was isolated by column chromatography of the evaporation residue (silica gel, 1:1 ethyl acetate:cyclohexane which converted to pure ethyl acetate).

Yield = 917 mg, m.p. 83-86° from ethyl acetate/cyclohexane. I.R.Vmax. (nujol) 3310, 1805, 1745, 1695 and 1645 cm<-1>. N.M.R..6(CDCl3) 1.97 (3H, s), 3.03 (1H, d,J=17Hz), 3.3-3.65 (5H, m), 4.07 (2H, d,J =7Hz), 4.79 (lH, wide t,J=7Hz), 5.10 (lH,s), 5.20 (2H, s), 5.68 (lH, d,J=3Hz), 5 .96 (lH, wide), 7.35 (5H, p).

Analysis. Found C, 60.98; H, 5.87; N, 7.39; c19H22N2°6

Claims C, 60.95; H, 5.92; N, 7.48.

Example 22

Sodium 9-O-(2-acetamidoethyl)-clavulanate

A solution of 469 mg of benzyl-9-O-(2-acetamidoethyl)-clavulanate in 15 ml of tetrahydrofuran was hydrogenated over 10% palladium/charcoal (150 mg) for 20 min. The solution was filtered through Celite and the filter cake washed with tetrahydrofuran. The combined filtrates were diluted with water and treated with a solution of 105 mg sodium bicarbonate in water. The tetrahydrofuran was removed on a rotary evaporator and the aqueous solution extracted twice with ethyl acetate. The aqueous solution was filtered through celite, evaporated and the residue dried over phosphorus pentoxide. yield = 279 mg..

I.R.Vmax. (KBr) 1782, 1690, 1620 (broad) and 1552 cm<-1>.

N.M.R. 6 (D20) 2.02 (3H, s), 3.13 (lH, d, J=17Hz), 3.25-3.75 (5H, m), 4.17 (2H, d, J=7Hz ), 4.92 (lH, wide t,J=7Hz), 4.98 (lH, s), 5.75 (lH, d, J=3Hz)..

Example 23

preparations

a. Sterile 9-O-(2-aminoethyl)-clavulanic acid (100 mg) can be dissolved

in sterile water for injectionB.P. (1 ml) to form a solution for injection. The 9-O-(2-aminoethyl)-clavulanic acid can

have been sealed in a glass container in a conventional manner. b. Sterile 9-O-(2-aminoethyl)-clavulanic acid (84 mg and amoxycillin sodium (equivalent to 250 mg amoxycillin) may be dissolved in sterile water for injection B.P. (1 ml) to form a solution for injection .The two antibiotics may be sealed

in a glass container in the conventional way.

c. 9-O-(2-aminoethyl)-clavulanic acid (125 mg) may be mixed with 20 mg of lactose and magnesium stearate and the mixture placed in a No. 3 gelatin capsule. This may be administered orally.

Description 1

N-benzyloxycarbonyl-aziridine

A stirred mixture of 8.6 g of aziridine in 150 ml of methylene chloride and 8 g of sodium hydroxide in 50 ml of water was cooled in an ice bath. 34.1 g of benzyl chloroformate was then added at such a rate that the temperature of the reaction mixture did not exceed 10°C.

When the addition was finished, the mixture was allowed to warm to 15°

within 1 hour. The organic phase was then separated, washed with

brine and dried over magnesium sulfate. The solution was then evaporated and the evaporation residue distilled under reduced pressure so that 19.1 g of N-benzyloxycarbonylaziridine was obtained in the form of an oil, b.p. 108-112°C at 0.5 mm.

I.R.V max. (film) 1730 cra"^.

N.M.R. fe(CDCl 3 ) 2.21 (4H, s), 5.15 (2H, s), 7.37 (5H, s). Analysis. Found = C, 67.97; H, 6.43; N, 7.90.

<C>10<H>11N02= c'67'78'H'6'21?N'79°-

Description 2

N-benzyloxycarbonyl-2,2-dimethylaziridine

A stirred mixture of 7.1 g of 2,2-dimethylaziridine in 75 ml of methylene chloride and 4.0 g of sodium hydroxide in 25 ml of water was cooled in an ice bath. 17.05 g of benzyl chloroformate was added dropwise at such a rate that the temperature of the reaction mixture did not rise above 10°C. When the addition was complete, the mixture was allowed to warm to room temperature for 1 hour. The organic phase was separated from and the aqueous phase extracted twice with chloroform. The combined organic phases were washed with brine, dried over magnesium sulfate and evaporated. The evaporation residue was distilled under vacuum to give 10.4 g of N-benzyloxycarbonyl-2,2-dimethylaziridine in the form of an oil, b.p. 106-110°C at 0.4 mm.

I.R. Vmax. (film) 1730 cm- .

N.M.R. 6(CDCl3), 1.30 (6H, s), 2.15 (2H, s), 5.17 (2H, s) 7.39 (5H, s).

Analysis. Found = C, 70.06; H, 7.64; N, 6.69.

C12H15N02= C' 70' 22' H'7'34?N'6/82.

Demonstration 1

The effectiveness of 9-O-(2-aminoethyl)-clavulanic acid can be illustrated by the following data: a. Mice were infected intraperitoneally with E. coli JT39. The curative effect of amoxycillin alone and in the presence of the compound according to the invention was determined in a conventional manner and the CD 2 value was calculated. The dosing schedule was 1 and 5 hours post-infection when subcutaneous administration was used and 1.3 and 5 hours post-infection when oral administration was used. b. The blood levels of 9-0-(2-aminoethyl)-clavulanic acid were determined in mice after subcutaneous and oral administration. The blood levels are in ^ug/ml c. In a further test, 9-0-(2-aminoethyl)-clavulanic acid was (10 mg/kg) and a comparison compound 9-O-(2-methyl-aminoethyl)-clavulanic acid (10 mg/kg) administered subcutaneously to mice and the resulting blood levels determined. The results (average of 5 animals each time) were as follows: d. The urinary recoveries of 9-O-(2-aminoethyl)-clavulanic acid and the reference compound 9-O-(2-methylaminoethyl)-clavulanic acid were also determined after subcutaneous administration of 10 mg/kg to mice. The results obtained were as follows: % urinary recovery of 9-O-(methylaminoethyl)-clavulanic acid % urinary recovery of 9-O-(aminoethyl)-clavulanic acid

e. Lithium-9-O-(2-N<1>,N'-ureidoethyl)-clavulanate was administered subcutaneously to four groups of 5 mice at a dosage of 20 mg/kg. The urinary recovery of the compound in each group was respectively 40 %, 36%, 19% and 27%.

Demonstration 2

The synergistic effect of some compounds according to the invention on the in vitro antibacterial activity of ampicillin was measured. The results are shown below [9-O-(2-N-methylamino-ethyl)-clavulanic acid is included for the sake of comparison].

( ) indicates some inhibition by the compound alone

Claims (25)

1. Process for preparing a compound of the formula (I): or a salt or ester thereof, where R is a hydrogen atom or a methyl group; R<2> is a hydrogen atom or a methyl group; 3 4 4 45 and R is a hydrogen atom or a COR-, CO-R ~ or CONR R - group, where R 4 is an alkyl group with up to 6 carbon atoms or a phenyl or benzyl group, and R~ <*> is a hydrogen atom or an alkyl group with up to 6 carbon atoms, characterized by the reaction of an ester of clavulanic acid in the presence of a catalyst, with an aziridine derivative of the formula (VI): where R<1> and R^ are as defined for formula (I) and R^ is a CO.R^-, 4 4 5 4 5 CO2R - or CO.NR R -group where R and R are as defined for formula (I), and then, if desired, execution of one or more of the following possible steps: (a) a compound of formula (I) or an ester thereof wherein R 3 is a benzyloxycarbonyl group is subjected to hydrogenolysis to produce a compound of formula (I) wherein R < 3 > is a hydrogen atom; (b) cleavage of the ester to form a salt or an acid; (c) esterification of a salt or acid prepared in the optional step (b). 2. Method as stated in claim 1, characterized in that R 3 is a hydrogen atom. 3. 'Procedure as stated in claim 1, characterized in that R 3 is a COR 4 group as defined in claim 1. 4. Method as stated in claim 1, characterized in that R 3 is a C02R 4 group as defined in claim 1. 5. Procedure as specified in claim 1, charac- 3 4 5 cert in that R is a CONR R group as defined in claim 1. 6. Method as stated in claim 3, characterized in that COR 4 is an acetyl, propionyl or benzoyl group. 7. Method as set forth in claim 4, characterized in that C02 R<4> is a methoxycarbonyl or benzyloxycarbonyl group. 8. Procedure as specified in claim 5, charac- 4 5 characterized in that CONR R is a methylaminocarbonyl or dimethylaminocarbonyl group. 9. Method as set forth in any of the claims .1 to 8, characterized in that CR 1 R 2 is a Cl^ share. 10. Method as set forth in any one of claims 1 to 8, characterized in that CR 1 R 2 is a CH(CH 3 ) moiety. 11. Method as set forth in any one of claims 1 to 8, characterized in that CR 1 R 2 is a C(CH 3 ) 2 moiety. 12. Method as stated in any one of claims 1 to 11, characterized in that a boron trifluoride etherate catalyst is used during the reaction of the compound of formula (V) with the ester of clavulanic acid. 13. Method as set forth in any one of claims 1 to 12, characterized in that the eventual step of cleaving the ester is carried out by hydrogenation or hydrolysis. 14. Process for preparing an ester of a compound of formula (VII): where R is as defined in claim 1, characterized by reaction of an ester of clavulanic acid with a compound of formula (VIII): where R^ is as defined in claim 1. 15. Process for the production of 9-0-(2-aminoethyl)-clavulanic acid, characterized by hydrogenation of a compound of formula (IX): 1 2 where C02A and C02A are groups which, by catalytic hydrogenation, are converted into CO-j H groups. 16. Method as stated in claim 15, characterized in that A 1 and A 2 are benzyl or substituted benzyl groups. 17. Method as stated in claim 16, characterized in that A 1 and A 2 are p-bromobenzyl, p-chlorobenzyl or p-nitrobenzyl groups. 18. Method for producing a compound of . formula 4 5(I) or a salt thereof, where R3 is COR4, C0_R4 or CO.NR R as defined in claim 1, characterized in that a corresponding ester is deesterified. 19. Synergistic pharmaceutical preparation, characterized in that it comprises 9-0-(2-aminoethyl)clavulanic acid and a penicillin or cephalosporin, as well as a pharmaceutically acceptable carrier. 20. Preparation as stated in claim 19, characterized in that the weight ratio between 9-0-(2-aminoethyl)-clavulanic acid and penicillin or cephalosporin is from 10:1 to 1:10. 21. Preparation as stated in claim 20, characterized in that the ratio is from 3:1 to 1:3. 22. Preparation as stated in any of claims 19 to 21 in unit dose form, characterized in that it comprises 50-500 mg of 9-O-(2-aminoethyl)-clavulanic acid. 23. Preparation as stated in claim 22, characterized in that it comprises 150-1000 mg of amoxycillin, ampicillin or an in vivo-hydrolyzable ester or an aldehyde or ketone adduct thereof or a pharmaceutically acceptable salt thereof. 24. Preparation as stated in any one of claims 19 to 23, characterized in that the 9-0-(2-aminoethyl)-clavulanic acid is in crystalline form. 25. Pharmaceutical preparation analogous to those stated in claims 19 to 24, characterized in that it comprises an alternative compound of formula (I) as defined in claim 1, or a salt or an ester thereof instead of 9-0-(2- amino-ethyl)-clavulanic acid..