GB2125038A - Amine salts of 6 beta -halopenicillanic acids - Google Patents

Abstract

This invention relates to penicillanic acid derivatives of the formula I <IMAGE> in which X stands for chlorine, bromine or iodine, Z stands for an amine and n is 1 or 2, and to pharmaceutical compositions containing the compounds of the invention and dosage units thereof. The 6 beta -halopenicillanic salts with amines are valuable in human and veterinary medicine.

Description

SPECIFICATION Amine salts of 6ss-halopenicillanic acids This invention relates to penicillanic acid derivatives of the formula I

in which X stands for chlorine, bromine or iodine, Z stands for an amine and n is 1 or 2, and to pharmaceutical compositions containing the compounds of the invention and dosage units thereof.

In the treatment of bacterial infections it is a serious problem that ss-lactamase producing bacteria occur with increasing frequency. These enzymes inactivate a variety of fi-lactam antibiotics, and it is well recognized that ss-lactamases from both gram-positive and gramnegative bacteria contribute significantly to the resistance of bacteria to ss-lactam antibiotics.

It has been found that the GP-halopenicillanic acids are potent inhibitors of fi-lactamases from a variety of gram-positive and gram-negative bacteria. This property makes the 6ss-halopenicil- lanic acids as well as the present salts valuable in human and veterinary medicine because they can protect fi-lactam antibiotics against inactivation when co-administered with these.

It has been reported (J. Org. Chem. Vol. 43, pp. 3611-3613, 1978; Proc. Natl. Acad. Sci.

U.S.A., Vol. 75, pp. 4145-4149, 1978; U.S. Patent No. 4,180,506 (Dec. 25, 1979); Biochem. J., Vol. 1 77, pp. 365-367, 1 979) that mixtures of 6ss- a n d 6 and 6a-bromopenicillanic acids are obtained either on epimerization of the latter or by selective hydrogenation of 6,6dibromopencillanic acid, the 6ss-bromo epimer being present in the reaction mixtures in estimated amounts from 5 to 15%. (In this specification percentages are by weight in respect of solid materials and by volume in respect of liquid materials.) The same literature has reported that such epimeric mixtures act as inhibitors of fi-lactamases, and since pure 6a-brnmopenicil- lanic acid has no effect on these enzymes, the inhibitory activity has been attributed to the 6ss- bromo isomer.

It is one object of the present invention to provide salts of 6ss-halopenicillanic acids of the formula I, suitable for medical use, for use as intermediates, or both.

The present salts of the 6fi-halopenicillanic acids are salts with pharmaceutically acceptable, non-toxic amines such as lower alkylamines, lower alkanolamines, e.g. diethanolamine or triethanolamine, procaine, cycloalkylamines, e.g. dicyclohexylamine, benzylamines, e.g. Nmethylbenzylamine, N-ethylbenzylamine, N-benzyl-fi-phenethylamine, N, N '-dibenzylethylenedi- amine or dibenzylamine, and heterocyclic amines. Some of these salts are readily soluble in water, whereas others are only slightly soluble.

The above list shall, however, only be considered illustrative for and not limiting the present invention.

The 6ss-halopenicillanic acids from which the present salts are derived may be prepared by various methods including their separation from mixtures containing the corresponding 6aepimers and/or 6,6-dihalo derivatives which may be present in the crude reaction mixtures.

The present salts can e.g. be obtained by treatment of a solution of the 6ss-halopenicillanic acid or a mixture containing the epimeric 6a- and 6ss- halo derivatives (see Examples 1 and 2 below) in a suitable organic solvent, e.g. methylene chloride, acetone, ethyl acetate or ether, with an equivalent amount of the organic base (preferably dissolved in the same solvent). The salts are obtained as crystalline precipitates which are filtered off and dried in vacuo.

The present salts are also valuable as intermediates in the isolation and purification of 6ss- halopenicillanic acids, as will appear from Examples 11 and 1 2 below.

It is also an object of the present invention to provide pharmaceutical compositions for use in the treatment of infectious diseases which contain as an active ingredient at least one of the compounds of the invention.

The compositions include forms adapted for enteral, parenteral, intramammary or topical use and may be used for the treatment of infections in mammals including humans.

The salts of formula I may be used for enteral, parenteral and topical administration.

Injectable or infusable compositions of the salts of 6ss-halopenicillanic acids of formula I are suitable, when high tissue levels of the GP-halopenicillanic acids are rapidly desired.

The active ingredient can be used as such or can be mixed up with carriers and/or auxiliary agents.

In such compositions, the proportion of therapeutically active material to carriers and auxiliary agents can vary between 1% and 95%. The compositions can be worked up to pharmaceutical forms of presentation such as tablets, capsules, powders, syrups, suspensions, solutions, including forms suitable for injection or infusion.

The carriers and/or auxiliary agents are pharmaceutically acceptable materials such as gelatine, lactose, starch, magnesium stearate, talc, vegetable and animal fats and oils, gum, polyalkylene, glycol, or other known carriers for medicaments, and diluents, binders, buffers, preservatives, disintegrants, coating materials, and the like in accordance with pharmaceutical practice in the manner well understood by those skilled in the art, in order to provide appropriate forms of pharmaceutical presentation, including sustained release preparations, double tablets, etc.

The compounds of the invention may be present in the composition as the sole agent or together with other therapeutic agents, in particular a p-lactam antibiotic or a synergistic combination of ss-lactam antibiotics. Suitable sslactam antibiotics for such compositions include not only those known to be highly susceptible to ss-lactamases, but also those which have a good degree of intrinsic resistance to fi-lactamases. Thus, suitable fi-lactam antibiotics for such compositions include benzylpenicillin, phenyoxymethylpenicillin, carbenicillin, methicillin, propicillin, ampicillin, amoxycillin, epicillin, ticarcillin, cyclacillin, cephaloridine, cephalothin, cefazolin, cephalexin, cefaclor, cephacetrile, cephamandole, cephapirin, cephradine, cephaloglycine, mecillinam, and other well known penicillins, cephalosporins or amidinopenicillanic acids or prodrugs thereof, such as hetacillin, metampicillin, the acetoxymethyl, pivaloyloxymethyl, ethyoxycarbonyloxyethyl, and phthalidyl esters of benzylpenicillin, ampicillin, amoxycillin or cephalogylcine, or the phenyl, tolyl, and indanyl a-esters of carbenicillin, ticarcillin or the like, or amidinopenicillanic acid pro-drugs, like pivmecillinam or bacmecillinam, or a similar 7ss- amidinocephalosporanic acid derivative.

When present in a pharmaceutical composition together with a sslactam antibiotic, the ratio of the compounds of the invention to the other sslactam antibiotic(s) is from 10:1 to 1:10 and advantageously may be from 3:1 to 1:3, calculated as the free acids, the range, however, not to be considered limiting the invention.

Another object of the invention resides in the selection of a dose of the compounds of the invention and a dosage unit of the compounds of the invention which dose and dosage unit can be administered so that the desired results are achieved without simultaneous secondary effects.

The compositions of the invention are conveniently administered in dosage units containing a total amount of from 0.025 g to 2.5 g, and preferably from 0.1 9 to 1.0 g, of the antibacterial agents, calculated as the free acids. The expression "antibacterial agents" shall here and in the following mean one or more GP-halopenicillanic acid salts of the invention, alone or combined with one or more known sslactam antibiotics, salts or pro-drugs thereof. When used in the veterinary practice, the dosage units may contain up to 25 g of the antibacterial agents.

By the term "dosage unit" is meant a unitary, e.g. a single dose capable of being administered to a patient, and which may be readily handled and packed, remaining as a physically stable unit dose, comprising either the active materials as such or a mixture thereof with a pharmaceutical carrier.

Similarly, for infusion, the compositions of the invention are given in dosage units containing up to 10 9 of the antibacterial agents in aqueous solution.

For parenteral use, e.g. injections, the compositions of the invention are given e.g. in an aqueous solution or suspension as a dosage unit containing from 0.1 g to 1 9 of the antibacterial agents, calculated as the free acids, to be dissolved or suspended immediately before use, or ready for use together with a pharmaceutically acceptable vehicle.

In the form of a dosage unit the compounds may be administered once or more times a day at appropriate intervals, always depending, however, on the condition of the patient.

Thus, a daily dose will amount to from 0.1 g to 30 g (corresponding to 1-425 mg/kg body weight/day), preferably from 0.2 g to 6 g of the antibacterial agents, calculated as the free acids.

The compositions of the invention may be used in the treatment of infections of inter alia the respiratory tract, the urinary tract, and soft tissues in humans and may also be used to treat infections in animals such as mastitis in cattle.

In compounded compositions containing other sslactam antibiotics, the latter will normally be present in approximately the same amounts as conventionally used when such sslactam antibiotics are the sole therapeutic agents, but under certain circumstances it may be appropriate to reduce the amounts thereof.

Particularly favoured compounded compositions will contain from 50-1,000 mg of the ss- lactam antibiotic, a salt or a pro-drug thereof, and the 6-halopenicillanic salt in an amount within the aforementioned ratios, and more suitably from 200-500 mg of the fi-lactam antibiotic, a salt or a pro-drug thereof, and from 25-250 mg of the 6ss-halopenicillanic acid.

The compounds of the present invention can be used for the treatment of humans and other mammals by administering an effective amount of the present compositions to patients suffering from infectious diseases.

The treatment may consist in administering compositions or compounded compositions of the invention, or in administering such compositions contaning the compounds of the invention alone together with the compositions containing other fi-lactam antibiotics. In the latter case, the two types of compositions may be administered simultaneously or at intervals and with varying proportions between the GP-halopenicillanic acid salt and the sslactam antibiotic.

Generally from 0.1 to 30 g of the antibacterial agents will be administered each day of the treatment, but more often from 500 to 6,000 mg of the antibacterial agents will be administered per day.

It shall be expressly understood that the above ranges of doses indicate the total amount of antibacterial agents, i.e. one or more compounds of the invention administered either alone, combined with, or given at intervals with other fi-lactam antibiotics as above.

The invention will be further described with reference to the following Preparations and in the following Examples which are not to be construed as limiting the invention.

Preparation 1 Potassium 6fi-bromopenicillanate A solution of potassium 6a-bromopenicillanate (7.64 g, 24 mmol) in 0.04 M aqueous disodium hydrogen phosphate (800 ml) was incubated for 72 hours at 30"C. According to an NMR-spectrum (D20) of a freeze-dried 5 ml sample, the epimeric mixture contained 10-12% of the 6fi-brnmo compound.

after addition of sodium chloride (160 g), the mixture was stirred at 0 C under a layer of ether (250 ml), and the pH of the aqueous phase was adjusted to 3 with 4 N aqueous hydrochloride.

The organic layer was separated, the aqueous phase was re-extracted with ether (100 ml), and the combined ethereal extracts were washed with saturated aqueous sodium chloride (10 ml), dried, and concentrated to about 40 ml at reduced pressure. The concentrated solution was subjected to dry column chromatography on silica gel (Silica Woelm TSC, Woelm Pharma, Eschwege, Western Germany). The column (f 5.6 cm, length 46 cm) was developed with etherpetroleum ether-formic acid, 70:30:0.1 (1200 ml), fractions á 2 cm were scraped out, suspended in ethyl acetate (10 ml/fraction), and samples of the supernatants were examined by thin-layer chromatography using the above mentioned solvent system. Fractions containing the pure, more polar 6 -bromopenicillanic acid were combined and eluted with ethyl acetate.The resulting ethyl acetate eluate was concentrated to about 50 ml at reduced pressure and washed thoroughly with water (6 X 5 ml) to remove the major amount of formic acid. To the organic layer was added water (40 ml), and the apparent pH of the mixture was adjusted to 7.2 by addition of 0.5 M aqueous potassium bicarbonate. The aqueous layer was separated and freezedried to afford 0.54 g of pure potassium 6ssbromopenicillanate as a colourless amorphous powder which crystallized from n-butanol, [a]2D0+ 240 (c = 0.2, H20).

The detailed FT proton NMR-spectrum (Fig. 1) showed signals at 8= 1.47 (s, 3H; CH3-2a), 1.59 (s, 3H; CH3-2ss), 4.27 (s, 1 H; CH-3), 5.52 and 5.58 (doublets, J = 4 Hz, 2H; CH-5a and CH-6a, confer Fig. 1a) ppm.

Instrument JEOL FX 100. Concentration 50 mg per ml. All data converted to tetramethylsilane as 0.00 ppm S-scale.

Preparation 2 Potassium 6,0-chioropenicillanate A solution of potassium 6a-chloropenicillanate (13.14 g, 48 mmol) in 0.04 M aqueous disodium hydrogen phosphate (1600 ml) was incubated for 96 hours at 30"C to yield, as revealed by an NMR-spectrum (D20) of a freeze-dried 5 ml sample of the reaction mixture, about 5-6% of 6ss-chloropenicillanic acid in admixture with the starting material.

To the reaction mixture was added sodium chloride (320 g) and ether (400 ml), and the pH of the aqueous phase was adjusted to 3 by addition of 4 N aqueous hydrochloric acid at 0 C with stirring. The organic phase was separated, the aqueous layer was re-extracted with ether (200 ml), and the combined ethereal extracts were washed with saturated aqueous sodium chloride (20 ml), dried, and concentrated to about 50 ml at reduced pressure. The concentrate was subjected to dry column chromatography on silica gel (as described in Preparation 1 for the separation of the corresponding 6-epimeric bromopenicillanic acids).Fractions containing the pure 6ss-chloropenicillanic acid were eluted with ethyl acetate, and the resulting solution was worked up in a similar manner as described in Preparation 1 to afford 0.68 g of potassium 6ss- chloropenicillanate as an amorphous powder which crystallized from n-butanol.

The NMR-spectrum (D20) showed signals at 8 = 1.48 (s, 3H; CH3-2a), 1.58 (s, 3H; CH3-2ss), 4.27 (s, 1 H, Cm3), 5.43 and 5.63 (2d, J = 4 Hz, 2H; C5 and CH-6a) ppm. Tetramethylsilane was used as external reference.

Preparation 3 Potassium 6ssbromopenicillanate A solution of potassium 6a-bromopenicillanate (15.28 g, 48 mmol) in water (320 ml) was adjusted to pH 9.0 with 1N aqueous sodium hydroxide and stirred for 24 hours at 30"C. During the reaction of pH of 9.0 was maintained in the solution by addition of 1 N aqueous sodium hydroxide via an automatic titrator. An NMR spectrum (D20) obtained from freeze-dried 1 ml sample of the solution indicated the presence of approximately 25% of the 6fl-brnmo compound in the epimeric mixture formed.

The mixture was worked up and purified by column chromatography as described in Preparation 1 to yield crystalline potassium 6-brnmopeniciIlanate identical with the product prepared in Preparation 1; [a120+ 253 (c = 0.5, 1 M phosphate buffer, pH 7).

Calculated for C8H > BrKNO3S: C, 30.19; H, 2.85; Br, 25.11; N, 4.40; S, 10.08%. Found: C, 30.16; H, 2.95; Br, 25.28; N, 4.33; S, 10.07%.

Preparation 4 Potassium 6ss-iodopenicillanate A. Acetoxymethyl 6-diazopenicillanate To a stirred solution of acetoxymethyl GP-aminopenicillanate (5.77 g, 20 mmol) and sodium nitrate (2.76 g 40 mmol) in a mixture of dichloromethane (120 ml) and water (120 ml) was added dropwise at 0-3'C 4 N aqueous sulphuric acid (7 ml).

After stirring at the low temperature for a further 30 minutes, the organic phase was separated, dried (Na2SO4), and concentrated to approximately 30 ml at reduced pressure.

This concentrate was used immediately in the following step.

B. Acetoxymethyl 6a-iodopenicillanate The concentrated solution of acetoxymethyl 6-diazepenicillanate from step A above was diluted with ice-cold acetone (180 ml), and to the stirred mixture was added dropwise at 0-3'C a solution of sodium iodide (9.0 g, 60 mmol) and 57% hydroiodic acid (7.4 ml) in water (15 ml). After stirring at 0-3"C for a further 25 minutes, the mixture was treated with solid sodium bicarbonate (10 g) and filtered. The filtrate was diluted with ethyl acetate (150 ml), acetone was removed at reduced pressure, and the remaining organic layer was separated, washed with 0.5 M aqueous sodium thiosulphate (2 X 100 ml), dried (Na2SO4). and concentrated to about 10 ml at reduced pressure.

This concentrated solution was subjected to dry column chromatography on silica gel (etherpetroleum ether, 4:6) to yield pure acetoxymethyl 6a-iodopenicillanate as a slightly yellowish oil.

The NMR spectrum (CDCl3) showed signals at 8 = 1.48 (s, 3H CH3-2oo), 1.63 (s, 3H; CH32a), 2.11 (s, 3H; COCH3), 4.56 (s, 1 H; CH3), 4.99 (d, J = 1.5 Hz, 1 H; Cm6), 5.45 (d, J = 1.5 Hz, 1 H; CH5), and 5.79 (ABq, J = 5.5 Hz, 2H; OCH20) ppm.

Tetamethylsilane was used as internal reference.

C. Potassium 6a-iodopenicillanate To a solution of acetoxymethyl 6a-iodopenicillanate (2.0 g 5 mmol) in 70% aqueous methanol (50 ml) was added 4 N aqueous hydrochloric acid (1.5 ml), and, after protection from light, the mixture was stirred at room temperature for 3 days. The mixture was poured into water (150 ml), extracted twice with ether (100 ml), and the combined ethereal extracts were washed with water (2 X 25 ml). To the organic layer was added fresh water (40 ml), and the pH in the aqueous phase was adjusted to 6.8 by addition of 1 M potassium bicarbonate with stirring. The aqueous phase was separated and freeze-dried to give potassium 6a-iodopenicillanate as an amorphous powder, which crystallized from acetone.

The NMR-spectrum (D20) showed signals at S = 1.46 (s, 3H; CH3-2a), 1.57 (s, 3H; CH3-2ss), 4.30 (s, 1 H; CH3), 5.24 (d, J = 1.5 Hz, 1 H; CH6), and 5.46 (d, J = 1.5 Hz, 1 H; CH5) ppm.

D. Potassium 6ssiodopenicillanate A solution of potassium 6a-iodopenicillanate (3.65 g, 10 mmol) in water (200ml) was stirred at 30'C for 20 hours, a constant pH of 9.0 being maintained in the reaction mixture by additions of 0.1 N sodium hydroxide via an automatic titrator. According to the NMR spectrum (D20) of a freeze-dried 1 ml-sample, the epimeric mixture of 6-iodopenicillanates thus formed contained approximately 30% of the 6ss-iodo compound.

To the mixture was added ether (150 ml), and the pH of the aqueous phase was adjusted to 3.0 by addition of 4 N hydrochloric acid with stirring. The organic phase was separated, the aqueous phase re-extracted with ether (50 ml), and the combined ethereal extracts were washed with saturated aqueous sodium chloride (2 X 20 ml), dried (MgS04), and concentrated to about 6-8 ml at reduced pressure.The concentrate thus obtained was subjected to dry column chromatography on silica gel (ether-petroleum ether-formic acid, 70:30:0.1), and, analogously to the procedure described in Preparation 1 for the separation and isolation of the corresponding 6ss- and 6a-bromo compounds, potassium 6ssiodopenicillanate was obtained in a crystalline state; [a]2D0 + 260 (c = 0.5, 1 M phosphate buffer pH 7).

The NMR spectrum (D20) showed signals at o = 1.49 (s, 3H; CHs-2a), 1.65 (s, 3H; CH3-2ss), 4.29 (s, 1 H; Cm3), 5.42 and 5.80 (2d, J = 3.5 Hz, 2H; CK5, and CK6) ppm.

Calculated for C8HgIKNO3S: C, 26.31; H, 2.48; I, 34.75; N, 3.84; S, 8.78%. Found C, 26.51; H, 2.58; 1, 34.91; N, 3.75; S, 8.80%.

Preparations 5 to 7 6ss-Halopenicillanic acids The crystalline 6fl-halopenicillanic acids listed in Table I below could be obtained as follows: a) By concentrations at reduced pressure of the ethyl acetate solutions containing the pure 6ss-halo compounds obtained after separation from the corresponding 6a-epimers by dry column chromatography on silica gel (as described in Preparation 1).

b) By liberation from aqueous solutions of the corresponding potassium salts under a layer of ether or ethyl acetate at pH 3 followed by separation of the organic phase, drying, and crystallization from ether-diisopropylether or ethyl acetate-hexane.

Table I:

[a] 2DO Prepara- X (c = 0.5, CHCI3) 1H-NMR data (S/ppm; CD3CN) tion C H and CH6 5 Br + 272' 5.48 and 5.54, 2d, J = 4.0 Hz 6 Cl + 264 5.38 and 5.58, 2d, J = 4.0 Hz 7 1 + 276' 5.35 and 5.74, 2d, J = 4.0 Hz The above acids decompose at about 80-100'C, therefore a well-defined melting point cannot be determined.

Preparation 8 6ss-Bromopenicillanic acid To a stirred suspension of potassium 6,6-dibromopenicillanate (11.91 g, 30 mmol) in dimethylformamide (30 ml) was added sodium borohydride (1.14 g, 30 mmol). In the course of approximately 30 minutes, the temperature in the reaction mixture rose to about 50"C, whereafter it slowly decreased to normal. After stirring at room temperature for 20 hours, water (100 ml) and ether (100 ml) were added, and the pH of the mixture was adjusted to 3 with dilute hydrochloric acid. The organic layer was separated, the aqueous layer was extracted with ether (25 ml), and the combined organic extracts were washed with water (25 ml). To the organic phase was added frech water (25 ml), and the pH of the aqueous phase was adjusted to 7 by addition of 1 M potassium bicarbonate with stirring.The aqueous layer was separated, and the water removed azeotropically by distillation with n-butanol in vacuo to give a crystalline mixture of the potassium salts of 6ss and 6a-bromopenicillanic acid in an approximate ratio of 55:45, as indicated by NMR spectroscopy.

The above potassium salts were dissolved in water (5 ml/g salt), and the pH of the aqueous phase was adjusted to 3 with 4 N hydrochloric acid under a layer of ethyl acetate 5 ml/g salt).

The organic phase was separated, washed with water, dried, and diluted with an equal volume of hexane. Seeding of the resulting solution followed by concentration at reduced pressure to about half the volume afforded crystalline 6-brnmopenicillanic acid which was filtered off, washed with ethyl acetate-hexane (1:1), and dried. Recystallization from ether-diisopropyl ether gave the analytical sample, (aTh0 + 268 (c = 0.5, CHCI3).

Calculated for C8H,OBrNO3S: C, 34.30; H, 3.60; Br, 28.53; N, 5.00; S, 11.45%. Found C, 34.47; H, 3.81; Br. 28.66; N, 4.99; S, 11.43%.

Example 1 Dicyclohexylammonium 6ssbromopenicillanate To a solution of 6,6-dibromopenicillanic acid (10.8 g, 30 mmol) in dimethylsulphoxide (75 ml) was added sodium cyanoborohydride (2.1 g; 90% pure), and the mixture was stirred until a clear solution was obtained (about 30 minutes). After standing for 72 hours, the mixture was diluted with water (75 ml) to precipitate unreacted starting material as dimethylsulphoxide solvate (C8HgBr2NO3S, C2H60S). The crystals were filtered off, washed with water and dried. The filtrate was extracted with methylene chloride (4 X 25 ml), and the combined extracts were washed with water (50 ml), dried (Na2SO4), and concentrated at reduced pressure to about half the volume.After addition of dicyclohexylamine (2.5 ml) and acetone (50 ml), the mixture was further concentrated to about 25 ml. Crystallization was induced by scratching, and, after standing for 1 hour at room temperature, the pure dicyclohexylammonium 6,8-bromopenicilla- nate was filtered off, washed with acetone, and dried. The compound exhibited no well-defined melting point, after darkening at about 170"C, it decomposed at 280-290"C.

Example 2 Dicyclohexylammonium 6ss-iodipenicillanate A. 6, 6-Diiodopenicillanic acid dimethylsulphoxide solvate To a cooled solution of 6,6-diiodopenicillanic acid morpholine salt (10.8 g, 20 mmol) in dimethylsulphoxide (20 ml) was added 1 N hydrochloric acid (20 ml), and crystallization was induced by scratching. After further addition of water (20 ml), the crystals were filtered off, washed with water, and dried to give an almost quantitative yield of the title compound which showed an ill-defined melting point with slow decomposition above 120-125"C..

Calculated for c8Hg12NO3S, C2H60S: C, 22.61; H, 2.85; I, 47.78; N, 2.64; S, 12.07%.

Found: C, 22.96; H,- 2.81; I, 47.64; N, 2.74; S, 12.14%.

B. Dicyclohexylammonium 6ssiodopenicillanate To a solution of 6,6-diiodopenicillanic acid dimethylsulphoxide solvate (5.31 g, 10 mmol) in dimethylsulphoxide (25 ml) was added sodium cyanoborohydride (0.7 g; 90% pure), and the mixture was stirred until a clear solution was obtained (about 30 minutes). After standing for 40 hours at room temperature, water (50 ml) was added, and the mixture was cooled to 5"C to precipitate unreacted starting material which was collected, washed with water, and dried. The filtrate was extracted with methylene chloride (3 X 25 ml), and the combined extracts were washed with water (2 X 10 ml), dried (Na2SO4), and carefully evaporated in vacuo. The residual oil was dissolved in acetone (25 ml), an equivalent amount of dicyclohexylamine was added, and crystallization was induced by scratching. After standing for 1 hour, the pure dicyclohexlyammonium 6ssiodopenicillanate was filtered off, washed with acetone, and dried. The compound showed no well-defined melting point, after darkening at about 150"C, it decomposed slowly above this temperature.

Examples 3 to 10 Further salts of 6fi-halopenicillanic acids with organic bases By treatment of a solution of the 6fl-halopenicillanic acid in a suitable organic solvent, e.g.

acetone, ethyl acetate or ether, with an equivalent amount of the organic base (preferably dissolved in the same solvent), the desired salt was obtained as a crystalline precipitate which was filtered off and dried in vacuo. The salts obtained by this method are listed in Table II below.

Table II

Example X n Z 3 Cl 1 dicyclohexylamine 4 Cl 2 N,N'-dibenzylethylenediamine 5 Br 2 N,N'-dibenzylethylenediamine 6 Br 1 procaine 7 1 1 dibenzylamine 8 1 2 N,N'-dibenzylethylenediamine 9 1 1 N-methylbenzylamine 10 1 1 procaine Example 11 GP-Bromopenicillanic acid A stirred suspension of dicyclohexylammonium 6ssbromopenicillanate (obtained according to Example 1) in ethylacetate-water (1:1) (20 ml/g salt) was adjusted to pH 3 with 4 N hydrochloric acid. Precipitated dicyclohexylammonium chloride was filtered off, and the organic layer was separated, washed twice with water, and dried.Addition of an equal volume of hexane followed by concentration of the solution at reduced pressure yielded pure, crystalline 6fi-brnmopenicillanic acid, identical with the compound described in Preparations 5 and 8.

Example 12 6fi-lodopenicillan ic acid By substituting dicyclohexylammonium 6ss-iodopenicillanate (obtained according to Example 2) for the corresponding 6ssbromopenicillanate in the procedure of Example 11, 6ss-iodopenicil- lanic acid was obtained as colourless crystals. Recrystallization from ether-diiospropyl ether afforded the analytical sample [a]2D0 + 278 (e = 0.5, CHCI3).

Calculated for C8H1olNO3S C, 29.37; H, 3.08; 1, 38.79; N, 4.28: S, 9.80%. Found: C, 29.46; H, 3. 13; 1, 38.96; N, 4.27; S, 9.81%.

Claims (18)

CLAIMS:

1. A compound of the formula I:

in which X stands for chlorine, bromine or iodine, Z stands for an amine and n is 1 or 2.

2; A compound according to Claim 1, which is a salt with a pharmaceutically acceptable, non-toxic amine.

3. A compound according to Claim 1, which is a salt with dicyclohexylamine.

4. A compound according to Claim 1, which is a salt with N,N'dibenzylethylnediamine.

5. A compound according to Claim 1, which is a salt with dibenzylethylenediamine.

6. A compound according to Claim 1, which is a salt with procaine.

7. A compound according to Claim 1, which is a salt with dibenzylamine.

8. A compound according to Claim 1, which is a salt with N-methylbenzylamine.

9. A compound according to Claim 1, substantially as hereinbefore described in any one of Examples 1, 2B and 3 to 10 of the foregoing Examples.

10. A pharmaceutical preparation in dosage unit form for entereal, parenteral, topical or intramammary treatment of patients (including animals) suffering from infectious diseases, which comprises as an active ingredient 0.025 g to 2.5 g of a compound as claimed in any one of Claims 1 to 9, if desired together with pharmaceutically acceptable, non-toxic carriers and/or auxiliary agents.

11. A pharmaceutical preparation in dosage unit form as claimed in Claim 10, containing from 0.1 g to 1.0 g of the active ingredient.

12. A pharmaceutical preparation in dosage unit form as claimed in Claim 10 or 11 in the form of tablets, pills, capsules, or suspensions.

1 3. A pharmaceutical composition containing a compound as claimed in any one of Claims 1 to 9 together with carrier substances and auxiliary agents, containing from 1 % to 95% of the active compound.

14. A compounded pharmaceutical composition as claimed in Claim 1 3 containing one or more compounds of Claim 1 together with one or more fi-lactam antibiotics or pro-drugs thereof, the ratio between the said compounds being from 1:10 to 10:1.

1 5. A compound pharmaceutical composition as claimed in Claim 14, in which said ratio is from 1:3 to 3:1.

1 6. A compounded pharmaceutical compositon as claimed in Claim 14 or 1 5, in which the ss-lactam antibiotic(s) is selected from ampicillin, amoxycillin, cephalexin, cefaclor, mecillinam, and pro-drugs thereof.

1 7. The use of a compound according to Claim 1, as an intermediate in the preparation of a 6ss-halo-penicillanic acid.

18. The use of a compound according to Claim 3 as an intermediate in the preparation of a 6ss-halopenicillanic acid in a substantially pure form.