SI9500072A - Process for the preparation and/or purification of clavulanic acid or its pharmaceutically acceptable salts or esters - Google Patents

Abstract

The process comprises: i) contacting impure clavulanic acid or its labile derivative, v solution in an organic solvent, with tertiary octylamine, ii) isolation of the clavulanic acid salt formed by tertiary octylamine; iii) conversion of the salt thus formed clavulanic acids with tertiary octylamine to clavulanic an acid or a pharmaceutically acceptable salt thereof or ester. Clavulanic acid and its salts and esters, prepared by the process of the invention are useful for the manufacture of medicines.

Description

Process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof

The present invention relates to clavulanic acids (I):

a new process for preparation and / or cleaning

and its pharmaceutically acceptable salts and esters.

Clavulanic acid is normally prepared by fermentation of a microorganism producing clavulanic acid, such as various microorganisms belonging to different strains (strains) of Streptomyces, such as S. clavuligerus NRRL 3585, S. jumoninensis NRRL 5741,

S. katsurahamanus IFO 13716 and Streptomyces sp. P 6621 FERM P 2804 as described e.g. in JP Kokai 80-162993. The resulting aqueous culture broth can be cleaned and concentrated by conventional methods comprising e.g. filtration and chromatographic purification, as shown in GB 1508977 and JP Kokai 80-62993, before extracting the aqueous solution with an organic solvent to obtain a solution of crude clavulanic acid in an organic solvent.

GB 1508977 illustrates, inter alia, that salts of clavulanic acid can be obtained by absorbing clavulanate anion in filtered soup on an anion exchange resin, eluting with it with an electrolyte, desalting the resulting solution, applying the desalinated solution to a further anion exchange resin, chromatographically using it electrolytes, desalinate the resulting solution and then remove the solvent. They can use this process to obtain acceptable yields of pure material, but the use of resin columns requires considerable investment and can limit production operations on a large scale. Therefore, it would be desirable to have an alternative process involving few steps using resin.

GB 1543563 illustrates a process for the preparation of clavulanic acid salts via lithium clavulanate precipitation. GB 1578739 describes various amine salts of clavulanic ^:: - - ² - ·. · 'Acids as pharmaceutical compounds. EP 0026044 illustrates the use of the tert.butylamine salt of clavulanic acid as a useful intermediate in the preparation of clavulanic acid. The salt is shown in BE 862211, but only as a suitable ingredient for pharmaceutical formulations. PT.94.908 describes the use of tri- (lower alkyl) amine salts and dimethylaniline salts of clavulanic acid in a clavulanic acid purification process, where they form the triethylamine salt of clavulanic acid and subsequently convert it to silyl diester of clavulanic acid. EP 0887178A discloses a process for the purification of clavulanic acid, in which organic amines can be used to form an intermediate amine salt with clavulanic acid in an impure solution. Also SI patent no. 9300296 describes a process for the preparation of clavulanic acid or its pharmaceutically acceptable salts and esters. The present invention provides a process for the preparation and / or purification of clavulanic acid or its pharmaceutically acceptable salts and esters.

From the amine of formula (II):

as an intermediate in the process for the preparation of clavulanic acid or its pharmaceutically acceptable salts and esters, wherein R1, R4 and R4 are selected from the following options:

(1) R1 is, optionally, a substituted cyclic group of the general formula:

R- (CHR <) _m where m is 0 or even Number 1 to 5, R is optionally substituted by an aliphatic hydrocarbon ring system containing 3 to 8 ring carbon atoms, R ^ is hydrogen or alkyl, amino or hydroxy- substituted alkyl, or substituted amino-substituted alkyl, or a group of the same general formula, or R1 above; R ^ or R ^ may be selected from the same groups from which R ¹ is selected, or from hydrogen, alkyl, alkenyl, amino- or hydroxy-substituted alkyl or alkenyl, or substituted amino-substituted alkyl or alkenyl; only with the exception of cyclohexylamine; or (2) each of R1, R4 and R4 may be the same or different and independently selected from hydrogen, alkyl, alkenyl, amino or hydroxy or alkoxy-substituted alkyl or alkenyl, or substituted amino-substituted alkyl or alkenyl, with the exception of tbutylamine, s-butylamine, Ν, Ν-dimethylethylamine, 1,2-dimethylpropylamine, neopentylamine and 2-amino-3,3-dimethylbutane; and with the proviso that if amine (II) is trimethylamine or triethylamine, the salt of clavulanic acid with amine (II) is formed by the reaction of clavulanic acid or its labile derivative in solution with an organic solvent with amine (II) or

- - ³ .....

its labile derivatives, and the salt is then isolated as or in a special phase from an organic solvent; or (3) R1 is optionally substituted aryl group of the general formula:

where R ^{4 is} hydrogen or one or more substituents and m is zero or an integer 1 to 5, R ² and R ³ are independently selected from hydrogen, alkyl, amino or hydroxy-substituted alkyl or substituted-amino-substituted alkyl or groups by the same general formula as R ¹ , with the proviso that if R ^{4 is} hydrogen and m is zero, then R ² and R ³ are not both methyl; but with the exception of benzyl tert.butylamine; or (4) R, and R ² and optionally R ³ together with the indicated nitrogen atom is the residue of an optionally substituted heterocyclic ring system which includes the nitrogen atom as a ring member, and optionally including one or more additional ring hetero atoms, and if R ³ is not part of a ring system, it is independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl or substituted amino substituted alkyl; only with the exception of piperidine; or (5) R1 is a group of the general formula:

5 ' ^R _χ

N ^ ΟΗ ^ ΝηΤ-ΟΗ ^ i / m

R wherein R ⁴ and R ^{5 are} independently hydrogen, alkyl, amino-substituted alkyl or substituted amino-substituted alkyl and R ² and R ^{3 are} independently selected from hydrogen, alkyl, amino or hydroxy-substituted alkyl, or substituted amino-substituted alkyl, and m is zero or an integer from 1 to 5; or (6) one or both of R 1 and R ² are hydrogen and R ³ represents an amino acid residue in which the carboxylate group of the amino acid may be esterified or in the form of an amide.

Unless otherwise defined herein, alkyl or substituted alkyl groups may conveniently contain 1 to 6 carbon atoms in an alkylner system. Suitable amino group substituents include alkyl.

- 4_

In option (1) above, the amine (II) is suitably different from the amine in which RA is a cycloalkyl group, and m is zero and R ^ and R ^ are both selected from cycloalkyl or hydrogen or C _n H2 _{n +} i, where n 1 to 7.

In Option (1) above, the cyclic group R may be suitably saturated, with m being suitably zero. Group R may be monocyclic or polycyclic, and each ring may conveniently contain 5, 6 or 7 ring carbon atoms, including ring-shared atoms in closed or bridged ring systems. Suitably, the cyclic group R may be unsubstituted.

Suitably, the amine (II) may include two or more cyclic groups R1 or a contracted ring system R1 or a substituted ring system R1, e.g. with one or more alkyl substituents such as alkyl. Suitably, R ⁷ and R 6 may be different from hydrogen, e.g. one or both may be alkyl or substituted alkyl.

Examples of such amines include cyclopentylamine, cycloheptylamine, N, N-dimethylcyclohexylamine, dicyclohexylamine, adamantylamine, N, N-diethylcyclohexylamine, N-isopropylcyclohexylamine, N-methylcyclohexylamine, cyclopropylamine, cyclobutylamine, norblobutylamine, cyclobutylamine, cyclobutylamine, cyclobutylamine.

In option (2) above, the amine (II) is suitably different from the amine in which R1 is hydrogen or C _n H2 _n + i, where n is 1 to 7 and R ⁷ and R 4 are both selected from hydrogen or ^c nH 2 n + l · ^k J ^er j ^{en] to7} ·

Suitably in Option (2) above, R1 may be an alkyl or substituted alkyl group of the general formula:

R ⁴

R ⁶ - R5.

wherein R ⁴ , R ⁵ and R 6 independently represent C 1-3 alkyl, or amino or hydroxysubstituted alkyl or substituted amino substituted alkyl.

R ⁴ , R 5 and R ⁴ may suitably be all alkyl, with two of R ⁴ , R ⁴ or R ⁴ methyl being suitably present. Examples of such amines include t-octylamine (2-amino-2,4,4-trimethylpentane) and t-amylamine. Alternatively, two of R ^4, R $ or R6 may be alkyl and one may be hydroxy - substituted alkyl. Examples of such amines include 1-hydroxy-2-methyl2-propylamine.

In Option (2) above, R ^J may alternatively be suitably C 1-20 alkyl, e.g. C 20-20 alkyl, C 1-2 alkenyl, C 1-2 () hydroxyalkyl or C 1-20 amino alkyl.

Examples of such amines include tri-n-propylamine, tri-n-octylamine, tri-n-butylamine, dimethylamine, i-propylamine, di-n-hexylamine, di-n-butylamine, diethylamine, 2aminoethanol, NN-diethylethanolamine, NN-dimethylethanolamine, ethanolamine, n-butylamine, nhexylamine, n-octadecylamine, N-ethylethanolamine, 1-hydroxyethylamine, diethanolamine, N-dimethylethanolamine, N-ethyldiethanolamine, 1,6-diamino hexane, triethanolamine, diisobutylamine, diisopropylamine, 2-methoxyethylamine, hydroxylamine, hydroxylamine, hydroxylamine, hydroxyethylamine , ethylamine, N-propylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, noctylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-prop-2-ylamine, nbut -2-ylamine, n-pent-2-ylamine, n-hex-2-ylamine, n-hept-2-ylamine, n-oct-2-ylamine, n-non2-ylamine, n-dec-2-ylamine , n-undec-2-ylamine, n-dodec-2-ylamine, n-hex-3-ylamine, n-hept3-ylamine, n-oct-3-ylamine, n-non-3-ylamine, n-dec -3-ylamine, n-undec-3-ylamine, n-dodec-3ylamine, n-oct-4-ylamine, n-non-4-ylamine, n-dec-4-ylamine, n-undec-4-ylamine , n-dodec-4ylamine, n-non-5-ylamine, n-undec-5-ylamine, n-dodec-5-ylamine and n-octadecylamine.

For option (3) above, amine (II) is suitably not an amine in which and R ^{3 is} selected from hydrogen or C _n H2 _n + j wherein n is 1 to 7 or benzyl or substituted benzyl.

In Option (3), the above suitable suitable substituent groups R 1 include C 1-8 alkyl as methyl, phenyl or optionally substituted phenyl, carboxylic or sulfonic acid groups and derivatives of such acid groups as esters (e.g. C 1-8 alkyl esters) and amides; nitro, and halogens as bromine. Suitable m may be zero, 1 or 2, and R ³ may be hydrogen or methyl. Suitably, R and R ³ can be hydrogen, or one of R ³ and R ³ can be hydrogen, and the other may be an aromatic group of the same general formula as RA.

Examples of such amines include 1-phenylethylamine, p-toluidine, p-aminobenzoic acid, p-bromoaniline, ethyl-4-aminobenzoate (benzocaine), benzylamine, diphenylamine, pmethylaminobenzene sulfonamide, m-nitroaniline, Ν, Ν'-benzylethine (dibenzylethine). ), diphenylmethylamine, 4-methylbenzylamine and 4-phenylbutylamine.

In Option (4) above, the ring system may be aromatic or aliphatic and may be monocyclic or polycyclic. Suitably, each ring in the system may have 5 or 6 ring atoms, including ring nitrogen atoms and including ring-shared atoms. Suitable optional substituents in the ring system include alkyl, amino, substituted amino, oxo and halogen. If the ring system includes additional ring hetero atoms in addition to the nitrogen atom shown, such hetero atoms may be conveniently selected from nitrogen and oxygen.

Examples of classes of such amines include substituted piperidines and optionally substituted piperidines, e.g. such wherein the substituents are selected from alkyl, hydroxyalkyl, halogen, amino, substituted amino and amino-substituted alkyl. Specific examples of such amines include N-ethyl piperidine, 2,6-dimethyl piperidine, 2methyl-N-hydroxypropyl piperidine (cyclo-methicane), 4-methyl piperazine, 1-methyl-4-phenyl piperazine, N-ethyl morpholine, hexamethylenimine , pyridine, 2-propylpyridine, 3-chloro-2: 6-aminopyridine, morpholine, 1,5-diazabicyclo [4,3,0] non-5-ene, 1,4-diazabicyclo [2,2,2] octane, pyrrolidone, quinuclidine and xanthinol.

In Option (5) above, both may be hydrogen, or one may be hydrogen and the other alkyl. and may be conveniently hydrogen or alkyl.

Examples of such amines include ethylene diamine, Ν, diet-diethylethylene diamine, N, N'diisopropylethylene diamine and triethylene tetramine.

In option (6) above, the amino acid may be a naturally occurring amino acid. The amino acid esters may be alkyl groups or substituted alkyl groups such as benzyl.

Examples of such amines include arginine, ornithine, histidine, lysine, benzylglycine, 3 amino-3-methylbutanoic acid, L-ethyl lysinate, L-methyl histidinate, methyl N-carbobenzyloxy-L-lysinate, methyl L-phenylalanine, ethyl glycyl glycine, ethyl glycyl glycine ethyl p-hydroxy phenyl glycinate, ethyl p-hydroxy phenyl glycinate, ethyl glycinate, ethyl L-tyrosinate, p-methoxybenzyl aminophenyl acetate, n-butyl α-aminophenyl acetate, methyl arginate, benzylglycine, benzyl phenylglycine, 1-nitrobenzyl, 1-nitrobenzyl butyl phenylglycine, p-methoxybenzyl phenylglycine, ethyl phenyl glycine, p-nitrobenzyl p-hydroxyphenyl-glycine, p-nitrobenzyl serine, n-butyl serine, methyl arginine, dimethyl glutamate, p-nitrobenzyl tyrosinate, p-nitrobenzyl glycinate, p-nitrobenzyl glycinate, p-nitrobenzyl α-amino-p-hydroxy-phenyl acetate, p-nitrobenzyl α-aminophenyl acetate, ethyl amino-p-hydroxy phenyl acetate, ethyl L-tyrosinate.

When amine (II) contains more than one nitrogen atom, clavulanic acid may form a salt with one or more nitrogen atoms, e.g. as in ΝΝ′-diisopropylethylenediamine diclavulanate.

Among the aforementioned amines, the preferred amines are phenylethylamine, t-amylamine, t-octylamine, 1-hydroxy-2-methyl-2-propylamine, cyclopentylamine, cycloheptylamine, 1adamantanamine, N-ethylpiperidine, N'-diisopropylethylenediamine and NN-dimethylethylamine .

The process of the invention comprises:

i) contacting the impure clavulanic acid or its labile derivative, in solution in an organic solvent, with tertiary octylamine, ii) isolating the clavulanic acid salt formed with tertiary octylamine, iii) converting the clavulanic acid salt thus formed with tertiary octylamine into a clavulanic acid or acceptable clavulanic acid salt or ester.

In the process of the present invention, a clavulanic acid salt with an amine (II) may be used to purify impure clavulanic acid during its preparation. Therefore, salt may be formed in a solution of clavulanic acid or a labile impurity-containing derivative thereof, by isolating the salt as a special phase, e.g. as a solid precipitate, from a solution containing residual impurities, then re-formulate clavulanic acid or form a pharmaceutically acceptable salt or ester thereof.

Suitable labile clavulanic acid derivatives include salts, e.g. an alkali metal salt such as lithium or sodium clavulanate, or esters such as silyl esters. Suitable labile derivatives of amine (II) include salts such as phosphate, borate, chloride, chlorate, perchlorate, bromide, toluenesulfonate, or alkanoates, such as acetate or ethylhexonoate. It is convenient to contact the amine (II) itself with only impure clavulanic acid in solution in an organic solvent.

The above process is conveniently carried out in an organic solvent which, although preferably substantially dry and containing e.g. below 6 g / L, e.g. 0.25-0.6 g / L of water may contain some water as solvents for clavulanic acid and amine (11). Suitable drying rates can be achieved by conventional water removal processes such as centrifugation. Water present in the solvent may be dissolved or in the form of separate phase droplets.

A solution of clavulanic acid in an organic solvent can be obtained by extracting an acidified aqueous solution of clavulanic acid, such as the fermentation liquid mentioned above. If the source of clavulanic acid is a culture broth resulting from the fermentation of a clavulanic acid-producing organism, such as e.g. above, to obtain an extract in a solvent with a suitable concentration of clavulanic acid for use in the present process, it may be desirable not to extract the culture broth itself, but to remove at least a portion of the suspended solids, e.g. by filtration before extraction. It may also be desirable to further pre-concentrate the aqueous clavulanic acid solution obtained from the fermentation such that e.g. aqueous clavulanic acid solution several times more concentrated with clavulanic acid than the starting culture broth, e.g. previously concentrated to a concentration of about 10-100 mg / ml, e.g. 10 - 40 mg / ml as 10 - 25 g / L of clavulanic acid.

Suitable methods for pre-concentration include absorption of clavulanic acid onto the anion exchange resin, followed by elution of clavulanic acid with it with an aqueous solution of electrolyte as sodium chloride, and optionally removing the salt. Acidification of the aqueous solution is also preferred, e.g. cultivation soups or pre-concentrated aqueous solutions prior to solvent extraction, e.g. at pH 1-3, e.g. pH about 1.5 - 2.5. It is also preferable to dry or remove the water from the extract in an organic solvent before forming a salt with an amine (11), e.g. under 6 g / L of water. The extraction is preferably carried out at a temperature of from 5 to 15 ° C.

Suitable organic solvents in which impure clavulanic acid can be contacted with an amine (II) include hydrocarbon solvents such as toluene and hexane, ethers as

- & --- ......

tetrahydrofuran, dioxane, diethyl ether, halogenated solvents such as dichloromethane and chloroform, ketones as acetone and methyl isobutyl ketone, and esters as ethyl acetate. Solvents that include a carbonyl group, e.g. the one of formula (III):

II

R ⁸ - C - R ⁹ (III) wherein C 1-6 is an alkyl group or a C 1-6 alkoxy group and R 16 is an alkyl group are examples of subclasses of suitable solvents, e.g. organic ketones or organic alkanoate esters. The present invention also encompasses the use of mixtures of such solvents.

More preferably, the organic solvent is one that can be used directly to extract the acidic aqueous solution; these are e.g. organic alkyl alkanoate esters, ketones and certain aliphatic alcohols, or mixtures thereof, such as ethyl acetate, methyl acetate, propyl acetate, n-butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, butanol and mixtures of such solvents. Of these, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate are most suitable. Suitable solvent mixtures include methyl ethyl ketone / methyl isobutyl ketone and tetrahydrofuran / methyl isobutyl ketone. The preferred solvent is ethyl acetate.

Suitable solvents for amine (II) include those mentioned above in which clavulanic acid can be dissolved or extracted; these are e.g. acetone, ethyl acetate, methyl isobutyl ketone and methyl ethyl ketone.

It seems particularly desirable to include ketones as acetone in the solvent system because they appear to inhibit the formation of clavulanic acid salts with amine (II) as oils.

In general, one equivalent of amine (II) or a small excess of one mole of clavulanic acid is used to prepare the clavulanic acid salt. Solutions of clavulanic acid and amine (II) may e.g. mix slowly and mix for a while after adding. The reaction between clavulanic acid or its labile derivative is conveniently carried out at a temperature below room temperature, e.g. at 0 to 15 ° C, e.g. 0 to 10 ° C, e.g. 0 to 5 ° C. A suitable concentration of clavulanic acid or its labile derivative in the solution is at least 1.0 g / L, e.g. in the range 1.0 to 4.0 g / L, clavulanic acid. It may be convenient to further concentrate the extract in the solvent to a concentration above this value, e.g. above 20 g / L.

In a further process, amine (II) can be introduced by mixing in a stream of a solution of clavulanic acid in a solvent so that salt is formed in the stream, either in solution or as particles, or as suspended droplets of dissolved salt in suspension. The amine (II) thus introduced can be introduced pure without additives or introduced as

--9 --- Solution in solvent, e.g. in the same organic solvent in which clavulanic acid is dissolved.

The desired salt of clavulanic acid can then be isolated with amine (II). In this way, the clavulanic acid salt with amine (II) can be separated from most or all impurities. The insulation can be carried out in the usual way, e.g. by centrifugation or filtration.

In an alternative isolation procedure, the clavulanic acid salt with amine (II) can be isolated from the organic solvent if the solvent is not completely or partially miscible with water by contacting the solvent with water to extract the salt, which may be in solution or suspension, from the organic solvent. solvents and form an aqueous solution of salt. Since the salts of clavulanic acid with amine (II) are quite soluble in water, this aqueous solution can be very concentrated, e.g. about 20 to 30% w / w

In this way, most of the organic impurities present in the clavulanic acid solution in the organic solvent remain in the organic solvent, while clavulanic acid is obtained in the form of its salt with an amine (11) in a relatively pure state in aqueous solution. The aqueous solution of clavulanic acid salt thus formed can be further treated in the usual way, e.g. is purified or converted to clavulanic acid or a pharmaceutically acceptable salt or ester thereof, as described below.

In a further alternative or additional process, clavulanic acid and an amine may be mixed in solution in a first organic solvent and then the salts extracted from the solution by the addition of a second organic solvent. Suitably, the first organic solvent may be an organic ester such as ethyl acetate, and the second solvent may be a halogenated solvent such as chloroform, an ether such as diethyl ether, a hydrocarbon such as toluene, an alcohol as ethanol, or a solvent of formula (III) above, such as e.g. acetone or methyl isobutyl ketone.

Some of the above mentioned salts of clavulanic acid are considered novel compounds and are, as such, a further aspect of the present invention: e.g. salts of clavulanic acid with phenylethylamine, t-amylamine, 1-hydroxy-2-methyl-2-propylamine, cyclopentylamine, cyclohexylamine, 1-adamantanamine, N-ethylpiperidine, NN-dimethylcyclohexylamine and NN'-diisopropylethylenediamine.

In one embodiment of the present invention, a clavulanic acid salt with an amine (II) may be used as a solvate in acetone. Acetone solvates in some cases have suitable stability and purity characteristics compared to the amine salts of clavulanic acid. Such solvates are particularly useful in the present invention as they can often be isolated as very pure and stable crystalline compounds.

The present invention also provides a salt of clavulanic acid with an amine (II) solvate in acetone. There may be some loss of insulation and / or drying

14 -, - acetone, because the solvation power may not be large, but the amount of acetone in the product is not critical.

The solvate in acetone can be formed by contacting clavulanic acid with amine (II) in the presence of acetone. Generally, a solution containing clavulanic acid can be mixed with at least the same volume of acetone together with amine (II) if the salt is precipitated.

Amin (II) can be dissolved in acetone and mixed with a solution of clavulanic acid in an organic solvent. Popular organic solvents include ethyl acetate, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, and mixtures of such solvents; ethyl acetate is preferred. Alternatively, the aqueous solution of the clavulanic acid salt with the amine (II) obtained by extraction with water as shown above may be mixed with acetone to form a solvate. Concentrated aqueous salt solution with excess acetone may conveniently be mixed to form a solvate.

Recrystallization of the clavulanic acid salt or solvate in acetone may be further suitable to further reduce the amount of impurities. A suitable recrystallization solvent is aqueous acetone. Such recrystallization is carried out in the usual way that e.g. The dissolved salt or solvate in water is treated with a small amount of acetone, filtered and then treated with larger volumes of acetone, optionally with stirring and / or cooling, to give a recrystallized product.

A further aspect of the present invention provides a process for the preparation of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, the method comprising converting a clavulanic acid salt of an amine of formula (II) into clavulanic acid or a pharmaceutically acceptable salt or ester thereof.

Pharmaceutically acceptable salts and clavulanic acid esters prepared according to the methods of the present invention include those described in GB 1508977 and 1508978, which are incorporated herein by reference.

Particularly suitable pharmaceutically acceptable salts include pharmaceutically acceptable salts of alkali and alkaline earth metals, e.g. sodium, potassium, calcium and magnesium salts. Of these salts, sodium and potassium are preferred, and potassium is preferred.

Suitable esters include those which can be vaccinated to obtain clavulanic acid or a salt thereof by chemical methods such as hydrogenolysis, or by biological methods.

A clavulanic acid salt with an amine (II), optionally in the form of a solvate thereof in acetone, can be converted to clavulanic acid or a pharmaceutically acceptable salt or ester thereof, e.g. by ion exchange in the case of free acid or salt, or by esterification.

The ion exchange can be performed using ion exchange resins, e.g. by guiding the salt solution through the weight of the cation exchange resin in sodium, potassium or calcium form. Suitable cation exchange resins include Amberlite IR 120 and equivalent resins.

Alternatively, ion exchange can be performed by reacting the protonated amine cation with a compound that is a precursor to a salt that may be e.g. a base such as carbonate, hydrogen carbonate or hydroxide, a pharmaceutically acceptable alkali or alkaline earth metal, or a salt of an organic carboxylic acid with a pharmaceutically acceptable cation, such as an alkali or alkaline earth metal, e.g. alkanoic acid salt of formula (IV):

R ¹⁰ -CO ₂ H (IV) in which R 6 is an alkyl group containing e.g. 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms. Examples of suitable salts include the acetate, propionate or ethylhexanoate salt, potassium 2-ethylhexanoate and sodium 2-ethylhexanoate being preferred. Typically, a clavulanic acid salt may be reacted with an amine (II) in solution with an alkali metal salt with an acid (IV) in solution or suspension in a suitable solvent, which may be an organic solvent, water or a mixture of water and an organic solvent such as isopropanol. Conveniently, solutions of the clavulanic acid salt can be mixed with the amine (II) and the salt precursor compound and the pharmaceutically acceptable salt is allowed to crystallize. Conveniently, the reaction can be carried out at a temperature below room temperature, e.g. at 0 to 15 ° C, e.g. at 0 to 10 ° C, preferably at 0 to 5 ° C. If a clavulanic acid salt is formed with an amine (11) in an aqueous solution, it can conveniently be precipitated by mixing excess acetone with the aqueous solution.

Suitable methods for esterification include:

a) reacting a clavulanic acid salt with an amine (II) with a compound of formula Q-R 4, wherein Q is an easily displaced group and R 4 is an organic group;

b) reacting the clavulanic acid salt with an amine (II) with an alcohol or thiol in the presence of a condensation promoter such as carbodiimide; and

c) reaction of a clavulanic acid salt with an amine (TI) with a diazo compound.

The above procedures should also cover those embodiments where the clavulanic acid salt with an amine (II) is first converted to clavulanic acid or another salt thereof and subsequently converted to the desired ester. Further details for esterification methods are

13 -.- shown in GB 1508977 and 1508978. The use of the present invention makes it easier to obtain clavulanic acid salts and esters in pure form than in the GB 1508977 and 1543563 processes.

The invention will now be illustrated by the following Examples, but by no means limited thereto. In the Examples, THF stands for tetrahydrofuran and RV for relative humidity.

13'-Example 1

In all the following Examples, the procedure was the same; the amine was mixed with a clavulanic acid solution in THF solution and rapid crystallization was observed to form a solid salt.

Amin Comment Salt stability D - (+) -? -Phenylethylamine crystalline solid stable> 70h, 20 ° C 50% RV t-octylamine crystalline solid stable> 70h, 20 ° C 50% RV 1-hydroxy-2-methyl-2- propylamine crystalline salt cyclopentylamine crystalline salt 50% RH, 20 ° C darkens after 72h cycloheptylamine crystalline salt 50% RH, 20 ° C darkens after 72h 1-adamantanamine crystalline salt 50% RH, 20 ° C stable> 70h N-ethylpiperidine crystalline salt 50% RH, 20 ° C stable> 70h N, N-dimethylcyclohexyl- crystalline salt 50% RH, 20 ° C amine stable> 90h ammonia crystalline salt > 70h, 50% RV some discoloration xanthinol white solid hygroscopic triethylene tetramine pale yellow solid low value p-methoxybenzyl-a- solid salt white after 16h dry atmosphere. aminophenyl acetate room temp., yellow after 16h 50% RV, room temperature

- 14--.

Amin Comment Salt stability n-butyl α-amino- phenylacetate solid salt yellow after 16h dry atmosphere. room temp. orange after 16h 50% RV room temperature methyl arginate solid salt white after 16h dry atmosphere.

room temp. orange after

16h50% RV room temperature

Example 2

In this case, however, a clavulanic acid salt was formed with the amine in solution in the first organic solvent and then caused to be separated from the solution as a solid precipitate by mixing with the second organic solvent.

2a. t-Octylamine - A stock solution of clavulanic acid in ethyl acetate containing about 28 g / L of clavulanic acid in impure form was prepared by extracting the impure fermentation broth of S. clavuligerus with ethyl acetate. Toxylamine (0.84 g) was added to 46 ml of this. After 10 minutes, the mixture was disturbed and fine crystals of salt were crystallized. Chloroform was added to an aliquot of the solution, which caused the formation of larger needles. Acetone was added to the further aliquot, again causing the formation of needle crystals, but smaller and slower than with chloroform. About 20 ml of chloroform was added to the remainder of the solution, followed by a volume of toluene approximately equal to the initial weight of the solution, which caused a significant amount of needle crystals to precipitate.

2b. Dicyclohexylamine - Dicyclohexylamine (1.18 g) was added to 46 ml of stock solution prepared as for 2a above. A clear solution was formed. Acetone was added to one aliquot, forming a fine amorphous precipitate.

2c. Ammonia - To 500 ml of stock solution prepared as for 2a above was added ammonia (21.1 ml of 2.5M ammonium 2-ethylhexanoate in ethyl acetate, i.e. about 1 equivalent). The addition of 50 ml of industrial methylated spirit (IMS) easily elicited the formation of a fine needle precipitate. However, it was observed that when using an impure clavulanic acid solution, as reflected by the color of the solution, a significant amount of colored impurities remained in the solution. Yield - 75%.

- 15 ...

2d. N, N-dimethylcyclohexylamine - To 500 ml of stock solution prepared as in 2a above was added N, N-dimethylcyclohexylamine (6.7 ml). It formed an oil at the beginning of the session. Acetone (150 ml) was added gradually to give a cloudy solution. An aliquot part of this cloudy solution was taken and diethyl ether was added to it, causing crystallization. Diethyl ether (100 ml) was added to the bulk of the solution, resulting in immediate crystallization. The crystals (13.4 g) were filtered and washed with acetone. 2e. t-Octylamine - To 500 ml of stock solution prepared as for 2a above was added t-octylamine (6.7 g). The solution was slightly mistaken. Acetone (20 ml) was added, which clarified the solution. Diethyl ether was added to an aliquot of the solution, resulting in immediate crystallization. Diethyl ether (55 ml) was added to the bulk of the solution, causing crystallization. The crystals were filtered and washed with acetone. Yield (12.9 g) represented 77% recovery of clavulanic acid from solution.

2f. Benzatin - Benzatin diacetate (9.16 g) was stirred with aqueous sodium hydroxide (5N, 10.15 ml). The aqueous solution was extracted with ethyl acetate (55 ml) and the extract added to the clavulanic acid stock solution prepared as for 2a above (1.0 L). Initially, oil was formed. Acetone (600 ml) was added and crystals formed (about 10 ml of diethyl ether were added), which is the residue from the test tube. Methyl isobutyl ketone (200 ml) was then added and the mixture was added to 2 L with acetone. The crystals formed were filtered and washed with acetone. The yield was 11.5 g, representing 59.1% of the recovered clavulanic acid.

Example 3

A solution of clavulanic acid in ethyl acetate (about 20 / tg / ml) was diluted with an equal volume of acetone. Then, an acetone solution of t-octylamine (1.25 mol equivalents) was added dropwise over 10 hours at 10 ° C. After further stirring for 1 hour, the precipitated crystals were collected, washed with acetone and dried in vacuo. A precipitate formed, which was white in color. Yield (adjusted for purity) = 76%.

Example 4

A 0.012M solution of benzyl clavulanate in THF was catalytically hydrogenated to form a solution of clavulanic acid in THF. To this solution (100 ml) was added 1aminoadamantane (25 ml 0.012M in THF) at room temperature. Rapid crystallization occurred. The solution was stirred for 30 minutes at room temperature and then at 5 ° C for 2 hours. The solution was then filtered and the crystals were washed and dried.

- 16.,.

Yield = 83%. The salt melting point was 190 - 192 ° C (decomposition).

Example 5

Benzyl clavulanate purified by Sephadex chromatography (20 g, 0.07 mol) was dissolved in tetrahydrofuran (distilled from calcium hydride, 400 ml) and 10% palladium-on-charcoal catalyst (5.7 g) was added. The mixture was hydrogenated by stirring at room temperature and at about 1.2 bar for 20 to 30 minutes. The state of the reaction was evaluated by thin layer chromatography using silica plates developed with ethyl acetate and visualized using triphenyltetrazolium chloride as a spray reagent. Clavulanic acid Rf 0.0, benzyl ester 0.4.

The reaction mixture was filtered and the filter cartridge was well washed. The combined filtrates (approximately 500 ml) containing clavulanic acid were treated by mixing with 2 amino-2,4,4-trimethylpentane (9.0 g, 0.07 mol) in dry THF (50 ml). Crystallization was observed within 1 minute. The mixture was stirred for 0.5 hours at room temperature and then at 5 ° C for 2 hours. The product was filtered off, washed with dry THF (100 ml) and dried under vacuum for 12 hours to give 23.0 g, 100% of the title salt from the ground. 160 - 170 ° C (decomposition).

Example 6

The preparation was carried out as in Example 5 using benzyl clavulanate (0.9 g, 0.003 mol) and treated the resulting clavulanic acid solution with 2-amino-2-methylpropane (0.22 g, 0.003 mol) in dry THF (10 ml).

The title salt (0.6 g, 73% yield) had a melt. 150 - 152 ° C (decomposition).

Example 7

The preparation was carried out as in Example 5 using benzyl clavulanate (0.9 g, 0.003 mol) and treated the resulting clavulanic acid solution with D (+) 1-methylbenzylamine in dry THF (10 ml). The mixture was stored at 5 ° C for two days while slow crystallization occurred. Filtration gave the title salt (0.6 g, 62% yield) from the ground. 125 ° C (decomposition).

Example 8

The aqueous solution of lithium clavulanate was mixed with the aqueous solution of alkylammonium phosphate. The precipitated lithium phosphate was filtered off and the salt amine clavulanate

- - I / -colorants with the addition of acetone. We have found that sodium clavulanate can also be used, but then ethanol must be added to induce sodium phosphate separation. Amine hydrochlorides are also used.

In this way, lithium clavulanate was used to prepare N-ethylpiperidine clavulanate and sodium clavulanate was used to prepare N-ethylpiperidine clavulanate.

Example 9

An impure solution of clavulanic acid, which is a crude extract of S. clavuligerus fermentation broth, was mixed with acetone (150 ml) after partial pre-purification by ion exchange (500 ml / wg / ml in ethyl acetate) and gradually treated with Ν, Ν-dimethylcyclohexyl solution. of amine (6.7 ml) in acetone (25 ml). An aliquot was removed and treated with diethyl ether and direct crystallization took place, grafting of the bulk resulted in rapid crystallization of the white plates, which was completed with the addition of ether (110 ml). The amine salt was filtered off and washed with acetone (3 x 100 ml) and air-dried. Yield = 13.4 g, 82% recovery, 64.9% found. (theoretically 61.0%).

Example 10

To the impure solution of clavulanic acid used in Example 9 (500 ml, 21 Mg / ml), which further contained acetone (20 ml), was added t-octylamine (7.6 g, 1.0 eq), which caused a slight disruption . The addition of diethyl ether (55 ml) resulted in the elimination of the amine salt as fine white needles, which were filtered off and washed with acetone.

Yield = 12.9 g, 77.2% recovery, 62.8% found. (theoretically 60.6%).

Example 11

An impure solution of clavulanic acid in ethyl acetate (IL, 10.14 / ig / ml) obtained by extraction from fermentation broth 5. clavuligerus with ethyl acetate and partial pre-purification by ion exchange was mixed with acetone (600 ml) and then treated with a solution of benzatin (6.15 g) in ethyl acetate (55 ml). The mixture began to crystallize as the addition of benzatin was nearing completion. Methylisobutyl ketone (200 ml) was then added to make the precipitation more complete. The crystals were filtered off and washed with acetone (3 x 100 ml). Yield = 11.5 g, 67.0% recovery.

- IH.

Example 12

The procedure of Example 11 was repeated using an impure, moist (about 1% water) solution of clavian acid in ethyl acetate. To separate the IL batches of this solution, an excess of ethylene diamine alone, ΝΝ′-diethylethylene diamine and NN′diisopropylethylene diamine was added with stirring, the amount of each amine being in excess of the amount needed to form the diammonium salt with clavulanic acid. After continuous stirring, a precipitate of salt formed. A further portion of the crystals was obtained by the addition of excess acetone. The precipitated diammonium salt was filtered off and washed with acetone.

The thus formed crystals of each of these diammonium salts were converted to potassium clavulanate by dissolving the salt in a minimal amount of water, followed by the addition of a solution of excess potassium 2-ethylhexanoate in isopropyl alcohol. After continuous stirring, a precipitate of potassium clavulanate was formed and filtered, washed with isopropyl alcohol and dried.

Example 13

A solution of clavulanic acid (0.0046 moles) in tetrahydrofuranyl (30 ml) was treated with a solution of trimethylamine in methanol (1.0 ml of a 25% w / v solution, about 0.0042 moles) to give a pale yellow solution. Crystallization was initiated by vaccination and condition at room temperature. Crystallization was rapid, gave fine needles and was terminated overnight at + 4 ° C. The product was filtered off, washed with a small volume of fresh solvent (about 5 ml) and dried in vacuo. The yield was 0.9 g (75%); m.p. above 310 ° C, slow tanning at temperatures above about 130 ° C.

Experiment B 24641: Det. C, 51.32; H, 7.15; N, 10.68% ^C 11 ^H 18 ^N 2 ° 5 requires C 51.16; H, 7.02; N, 10.84%

Experiment A 15230: Imidazole 77.2; 76.4% (calc. 77.1% about 99.5% purity)

Water 1.18; 1.34%

The compound (like a cream colored fine needle) breaks down in air for several days, absorbs water and slowly turns yellow.

- 19. Example 14

We included two preparations of the above compound because each gave a slightly different result. The former yielded a modest yield of water-containing product to the extent that it corresponded to the hemihydrate, while the latter yielded predominantly anhydrous material, albeit in small yield.

14A. Clavulanic acid (0.00346 moles) in tetrahydrofuran (25 ml) was treated with triethylamine (0.4 g, 0.00346 moles) and stirred to give a homogeneous clear solution. Crystallization was initiated by grafting and terminated overnight at + 4 ° C. The product was filtered off and dried in vacuo. Yield 0.7 g (63%) as large dirty white needles.

Experiment B 24639: Found. C, 54.74; H, 7.95; N, 8.94%

C14H24N2O5 requires C, 56.05; H, 8.00; N, 9.33% ^C 14 ^H 24 ^N 2 ° 5/2 ^H 2 ° requires C, 54.36; H, 8.14; N, 9.05%

Experiment A 15220: Imidazole 61.0; 61.1% (calculated 64.4%, about 95.0% purity)

Water 2.64% (hemihydrate requires 12.91%)

14.B Clavulanic acid (0.021 mol) in tetrahydrofuran (60 ml) was treated with triethyl amine (2.1 g, 0.021 mol) and the resulting clear solution was cleaved with an authentic salt. The product began to crystallize in the form of long needles at room temperature, ending the process at + 4 ° C overnight. The product was collected by filtration, washed on the filter with fresh solvent (about 10 ml) and diethyl ether (about 20 ml) and finally dried in vacuo to give a dirty white crystalline product.

Yield 1.7 g (27%).

Experiment B 24676: Det. C, 56.07; H, 7.83; N, 9.32%

C14H24N2O5 requires C, 56.05; H, 8.00; N, 9.33%

C14H24N2O5 / 2H2O requires C, 54.36; H, 8.14; N, 9.05%

Experiment A 15268: Imidazole 65.1; 65.1% (Calc. 66.3%, about 98.2% purity)

Water 0.9% [ο;] ₀ 24 + 47.00 c (c = 0.2% in water)

- ζΡ

Like trimethyl amine salt, the product also breaks down in the air for several days. These two examples explain the formation of very pure salts of clavulanic acid from solutions of clavulanic acid in organic solvents.

Example 15

Separate trimethylamine clavulanate and triethylamine clavulanate samples from Examples 13 and 14 were dissolved in a minimum amount of cold water. To these solutions, a strong solution of potassium 2-ethylhexanoate in isopropanol was added with stirring. After continuous stirring, the potassium clavulanate crystals were separated and could be filtered off, washed with cold isopropanol and dried.

Example 16

An impure aqueous solution of clavulanic acid obtained from S. clavuligerus fermentation broth by preliminary purification comprising ion exchange chromatography or as generally indicated above containing about 17.1 g / L was acidified to pH 2.0 with 25% vol. / vol. sulfuric acid and then continuously extracted into ethyl acetate. The ethyl acetate extract was cooled to 2 ° C, the water was removed by centrifugation, then dried with MgSC> 4, and then run through a CPG carbon column. At this stage, the ethyl acetate extract contained 6.02 g / L of clavulanic acid and was then concentrated by evaporation to a concentration of 25.7 g / L of clavulanic acid and used at this concentration. The humidity level of the concentrate was about 0.26 vol./vol. %.

7.8 ml of t-octylamine was mixed with 25 ml of fresh ethyl acetate. This mixture was slowly added to 2 L on clavulanate-rich ethyl acetate extract, diluted again to a titer of 23.0 g / L with fresh ethyl acetate, with rapid stirring. The slurry was stirred for a further hour at 5 ° C. The t-octylamine clavulnate was then isolated by filtration and washed with ethyl acetate. The final drying was carried out overnight in a vacuum oven at 20 ° C with nitrogen emission. Product weight = 6.13 g.

Example 17 g of the amine salt prepared in Example 16 was dissolved in 97 ml of isopropanol. The product did not dissolve easily and we found that careful heating to 24 ° C was required to achieve complete dissolution. Within 10 minutes, 14 ml of 1.5N potassium 2-ethylhexanoate in isopropanol was added. The slurry was then stirred for 1.5 hours at 5 ° C.

The potassium clavulanate product was then filtered off, washed with small amounts of isopropanol, then acetone and dried overnight in vacuo with nitrogen at 20 ° C. Product weight = 3.16 g.

Example .18

The filtered (RVF) fermentation broth of S. clavuligerus containing 2 g / L of clavulanic acid was acidified to pH 1.6 with 25% vol./vol. sulfuric acid and then continuously extracted into ethyl acetate. The extract in the solvent was cooled to 3 ° C, the water was removed by centrifugation, then dried with MgSC> 4, and then run through a CPG carbon column. The charcoal-treated extract was then concentrated by evaporation to a concentration of about 20 g / L of clavulanic acid with a moisture content of about 0.06 vol./vol. %.

13.5 ml of t-octylamine were mixed with 43 ml of fresh ethyl acetate. This mixture was slowly added to 400 ml on clavulanate-rich ethyl acetate extract, with a titer of 20 g / L of clavulanic acid, with rapid stirring. The slurry was stirred for a further hour at 5 ° C. The t-octylamine clavulnate was then isolated by filtration and washed with ethyl acetate. The final drying was carried out overnight in a vacuum oven at 20 ° C with nitrogen emission. Product weight = 12.44 g.

Example 19 of the amine salt prepared in Example 18 was dissolved in 213 ml of isopropanol. The product did not dissolve easily even after careful heating to 24 ° C. Water (3.75 ml) was added to allow dissolution. After the solution was obtained, isopropanol (100 ml) was added to reduce the water content before crystallization. 30 ml of 1.5N potassium 2-ethylhexanoate in isopropanol was added over 15 minutes. The slurry was then stirred for 1.5 hours at 5 ° C. The potassium clavulanate product was then filtered off, washed with small amounts of isopropanol, then acetone and dried overnight in vacuo, under nitrogen evolution at 20 ° C. Product weight = 7.29 g.

Claims (18)

PATENT APPLICATIONS A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting impure clavulanic acid as its salt with an alkali metal in solution in an organic solvent, with an amine of formula (II) R '* Vi-R ³ (Π) where R 1 is a group of the general formula ^R ₁ -CH ₂ CH, NH-1-CH, CH ₂ i * m R 2 and R 4 are independently hydrogen, alkyl, amino substituted alkyl, or substituted, amino substituted alkyl, and R 1 and R 4 are independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted, amino substituted alkyl, and m is zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. Process according to claim 1, characterized in that the alkali metal salt is a sodium or lithium salt. 3. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting an impure clavulanic acid or a labile derivative thereof in a solution in an organic solvent containing between 0.25 and 0.6 g / l of water with an amine of formula (II) R ¹ N-R (Π) where R1 is a group of the general formula R ⁵ Y1-fOH ₂ CH ₂ NH-J-CH ₂ CH ₂ R ⁴ wherein R ⁴ and R 8 are independently hydrogen, alkyl, amino substituted alkyl, or substituted amino substituted alkyl, and R 4 and R 4 are independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted, amino substituted alkyl, and m is zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. 4. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting the impure clavulanic acid or its labile derivative in a solution in an organic solvent, which is dried by removing water from the solvent by centrifugation, with an amine of formula (II) R ⁵ You — R ³ R ² συ where R ^ is a group of the general formula ^R \ N-f CH ₂ CH ₂ NH- ^ CH ₂ CH ₂ 24 wherein and independently are hydrogen, alkyl, amino substituted alkyl, or substituted amino substituted alkyl, and R 2 and independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl or substituted amino substituted alkyl, m being zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. 5. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) a) obtaining the impure clavulanic acid in the soup resulting from the fermentation of the microorganism of the clavulanic acid producer b) removal of at least part of the suspended solids in the soup; c) contacting the resulting impure clavulanic acid or its labile derivative in solution in an organic solvent with an amine of formula (II) R ¹ \ ir ³ r.2 where R1 is a group of the general formula ^R \ 'n -f ΟΗ ₂ ΟΗ ₂ ΝΗ- ^ ΟΗ ^ Η ₂ p * m ^z wherein and R8 are independently hydrogen, alkyl, amino-substituted alkyl, or substituted, z amino substituted alkyl, and R 1 and R 2 are independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted amino substituted alkyl, and m is zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. Process according to claim 5, characterized in that at step i) b) the suspended solids are removed by filtration. Process according to claim 6, characterized in that the filtered broth of impure clavulanic acid is pre-concentrated. The method of claim 7, wherein the aqueous clavulanic acid solution is pre-concentrated to a concentration of 10 to 100 mg / ml. The method of claim 7, wherein the aqueous clavulanic acid solution is pre-concentrated to a concentration of 10 to 40 mg / ml. 10. The method of claim 7, wherein the aqueous clavulanic acid solution is pre-concentrated to a concentration of 10 to 25 mg / ml. Process according to any one of claims 7 to 10, characterized in that the pre-concentration process is carried out by absorbing clavulanic acid onto the anion exchange resin, followed by elution of clavulanic acid with it by means of an aqueous electrolyte solution. Process according to claim 11, characterized in that the electrolyte is sodium chloride. Process according to claim 11 or 12, characterized in that the salt is removed from the eluent. 14. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting an impure clavulanic acid or a labile derivative thereof in a solution in an organic solvent selected from the group consisting of hydrocarbon solvents, ether solvents and halogenated solvents with an amine of formula (II) R ¹ (II) wherein R ¹ is a group of the general formula R ⁴ N-f CH ₂ CH ₂ NH-1- CH ₂ CH ₂ wherein R ₂ and R 4 are independently hydrogen, alkyl, amino substituted alkyl, or substituted amino substituted alkyl, and R 2 and R 4 are independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted amino substituted alkyl, and m is zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. Process according to claim 14, characterized in that the solvents are selected from the group consisting of toluene, hexane, tetrahydrofuran, dioxane, diethyl ether, dichloromethane and chloroform. 16. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting the impure clavulanic acid or its labile derivative in solution in an organic solvent with an amine of formula (II) R ⁴ R ³ * wherein R1 is a group of the general formula R ⁵ 'n -t ch ₂ ch ₂ nh-f- ch ₂ ch ₂ - R ^{4 m} where R ⁴ and R ⁴ are independently hydrogen, alkyl, amino substituted alkyl, or substituted amino substituted alkyl, and R 2 is independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted amino substituted alkyl, and m is zero or an integer from 1 to 5; wherein the amine is introduced by interfering with the flow of a clavulanic acid solution in an organic solvent; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. 17. A process for the preparation and / or purification of clavulanic acid or a pharmaceutically acceptable salt or ester thereof, characterized in that it comprises i) contacting the impure clavulanic acid or its labile derivative in solution in an organic solvent with an amine of formula (II) R ' N-r ' R ² (II) where R 1 is a group of the general formula ^{R 1} N-f CH, CH ₂ NH-J-CH, CH ₃ <m * wherein R ^ and R ^ are independently hydrogen, alkyl, amino-substituted alkyl, or substituted, amino-substituted alkyl, and R ^ and R ^ independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted amino substituted alkyl, m being zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid, wherein isolation of the amine salt of clavulanic acid from an organic solvent which is completely or partially immiscible with water is carried out by contacting the solvent with water by extracting the salt from the organic solvent and forming an aqueous salt solution. ; iii) converting the salt thus formed into clavulanic acid or a pharmaceutically acceptable salt or ester thereof. R ' N-R (H) 18. A process for the preparation and / or purification of the clavulanic acid sodium, potassium or calcium salts, characterized in that it comprises i) contacting an impure clavulanic acid or a labile derivative thereof in a solution in an organic solvent with an amine of formula (II) wherein R ^{3 is a} group of the general formula ^{R 1} N-tCH ₂ CH ₂ NH -} - CH ₂ CH ₂ R ^{4 m} wherein R ⁴ and R ^{3 are} independently hydrogen, alkyl, amino-substituted alkyl, or substituted, amino-substituted alkyl, and R ² and R ^{3 are} independently selected from hydrogen, alkyl, amino or hydroxy substituted alkyl, or substituted amino substituted alkyl, and m is zero or an integer from 1 to 5; ii) isolation of the formed amine salt of clavulanic acid; iii) converting the salt thus formed into the sodium, potassium or calcium salts of clavulanic acid by ion exchange, the ion exchange being carried out by guiding the amine salt solution through a cation exchange resin in the sodium, potassium or calcium form.