NO161677B - PROCEDURE FOR THE PREPARATION OF 2BETA-CHLORAMETHYL-2ALFA-METHYLPENAM-3ALFA-CARBOXYLIC ACID SULPHON. - Google Patents

Description

The present invention relates to a process for the preparation of a 2B-chloromethyl-2a-methylpenam-3a-carboxylic acid sulfone with the formula

a pharmaceutically acceptable salt of the acid or a physiologically hydrolyzable ester of the acid.

The assumed connection between the resistance exhibited

of certain bacteria to ε-lactam antibiotics and the ability of such bacteria to produce s-lactamases, has led to an intense search for ε-lactamase inhibitors. Clavulanic acid is an example of such a compound that is currently being studied extensively. Another B-lactamase inhibitor has the acid form structure

and is known from European patent application 2927, published on 11 July 1979.

The connection with the structure

is known from US patents 4,036,847, 4,009,159, 3,993,646, 3,989,685 and 3,954,732. From US patent 4,155,912, 2-penem-3-carboxylic acid compounds with the formula as well as esters and salts are known. See also Farmdoc Abstracts 82090A, 10336B and 443337B. The connection (under the number CP-4 5899) with the structure

is an irreversible e-lactamase inhibitor with excellent solution stability. It has weak antibacterial activity and enhances the in vitro and in vivo activities of ampicillin over-lactamase-producing strains [A.R. English et al., Antimicrobial Agents and Chemotherapy, vol. 14, 1978, p. 414-419, Aswapokee et al., J. Antibiotics, vol 31(12), Dec. 1978, p. 1238-1244 as well as Derwenfs Farmdoc Abstracts 89627A and 73866B].

The above pharmaceutically acceptable salts include non-toxic metal salts, such as sodium, potassium, calcium and magnesium salts, the ammonium salt and substituted ammonium salts, e.g. salts of non-toxic amines, such as trialkylamines (e.g. tri-ethylamine), procaine, dibenzylamine, N-benzyl-o-phenethylamine, 1-ephen-amine, N,N'-dibenzyl-ethylenediamine, dehydroabiethylamine, N, N'bis(dehydroabiethyl)ethylenediamine, N-(lower)-alkylpiperidine (eg, N-ethylpiperidine) as well as other amines have been used to form pharmaceutically acceptable salts of penicillins and cephalosporins. The most preferred salts are the alkali metal salts, namely the sodium and potassium salts and the ammonium salt.

The term "physiologically hydrolyzable esters" refers here to such pharmaceutically acceptable esters that are hydrolyzed to the free acid form in vivo. Examples of suitable physiologically hydrolysable esters are phenacyl, acetoxymethyl, pivaloyloxymethyl, a-acetoxyethyl, a-acetoxybenzyl, a-pivaloyloxyethyl, phthalidyl(3-phthalidyl), indanyl(5-indanyl), methoxymethyl, benzoyloxymethyl, a-ethyl-butyryloxymethyl , propionyloxymethyl, valeryloxymethyl, isobutyryloxymethyl, 6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]-heptane- 2-carbonyl-oxymethyl and 6-[(R)-2-amino-2-p-hydroxyphenylacetamido]-3-3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]-heptane-2 -carbonyloxymethyl. The most preferred esters are acetoxymethyl, pivaloyloxymethyl, methoxymethyl, phthalidyl, 5-indanyl, 6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0]heptane-2-carbonyloxymethyl and 6-[(R)-2-amino-2-p-hydroxyphenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0 ]heptane-2-carbonyloxymethyl.

The method according to the invention is characterized by one in order

a) oxidizes, such as with KMnO 4 , H 2 O 2 or a similar peroxide or a similar peracid, an ester of the formula

to form an ester sulfoxide of the formula

and then

b) reacts the ester sulfoxide with a metal in acid, such as with zinc in glacial acetic acid, to produce the desired acid or

the salt, and then if desired

c) esterifies the acid or its salt to form a physiologically hydrolyzable ester of the acid.

Many different oxidizing agents can be used which are known for oxidizing sulfides to sulfones. However, particularly suitable reactants are alkali metal permanganates, e.g. potassium permanganate, and organic peracids, e.g. 3-chloro-benzoic acid.

"Skellysolve B" is a petroleum ether fraction with a boiling point of 60-68 C which mainly consists of n-hexane.

The method according to the invention will be explained in more detail in the following examples.

Example 1

Production of BL-P2013

This method simplifies the preparation of BL-P2013 by eliminating the previous use of catalytic reduction.

(see p. 633 in "Cephalosporins and Penicillins", edited by Edwin H. Flynn, Academic Press, New York, 1972). 30 g (0.1 mol) of 6α-bromopenicillanic acid sulfoxide (1) was dissolved in 1 liter of dry CH 2 Cl 2 followed by the addition of 16.2 ml (0.2 mol) of pyridine and 29.8 g (0.2 mol) of trichloroethane . Then 20 g (0.1 mol) of dicyclohexylcarbodiimide were added, and the mixture was stirred at 22°C for 16 hours. Dicyclohexylurea began to precipitate, at the end it was removed by filtration. The filtrate was washed with 200 ml of 5 percent aqueous sodium bicarbonate, 200 ml of 10 percent phosphoric acid and 100 ml of saturated aqueous sodium sulfate. The organic phase was dried over sodium sulfate at 5°C for 30 minutes, filtered and evaporated to an oil. Diethyl ether was added, and during scraping 27 g (63% yield) of product 2 crystallized. 26.5 g (0.062 mol) of compound 2 was dissolved in 500 mL of p-dioxane, and 8.5 mL (0.078 mol ) benzoyl chloride and 8.75 ml (0.078 mol) quinoline. The solution was boiled with reflux for 4 hours and then poured into 1100 ml of water, and the product 3 was extracted into 2 x 400 ml of ethyl acetate. The ethyl acetate extracts were combined and washed sequentially with 200 ml of 5% aqueous sodium bicarbonate, 200 ml of 5% phosphoric acid and 200 ml of saturated aqueous sodium sulfate, dried over sodium sulfate at 5°C for 30 minutes and evaporated to an oil (3), which was used as such in the next reaction.

Compound 3 obtained in the previous step was dissolved in 1 liter of glacial acetic acid, and with stirring at 22°C, a saturated aqueous solution of KMnO^ was added dropwise until a light pink color was stable, i.e. one drop placed on a piece of filter paper gave a light pink color. During cooling, 30 percent HjOj was then added dropwise until a clear solution was obtained. Some white precipitate was present. The solution was poured into 2.5 liters of water, and the product 4 was extracted into 3 x 500 ml of ethyl acetate. The ethyl acetate was washed with 5% aqueous sodium bicarbonate until neutral, i.e. addition no longer caused bubbling, dried over sodium sulfate and evaporated, leaving 4 as a residue. This was left at 10°C for one day and was then treated with "Skellysolve B", whereby a yield of 9.1 g of solid 4 was obtained. The yield was 28% of the theoretical for steps 2 and 3 combined.

(see US Patent 4,164,497).

3.75 g of zinc powder was slurried in 5 ml of glacial acetic acid and cooled to 5°C. To this mixture was added a solution of 3 g (0.0057 mol) of compound 4 in 15 ml of dimethylformamide, and the resulting slurry was stirred at 5°C for 2.5 hours.

The zinc was then filtered off, and the pale yellow solution was poured into 80 ml of 5 per cent aqueous hydrochloric acid. This mixture was extracted with 3 x 25 ml of ethyl acetate. The combined ethyl acetate extracts were extracted with 3 x 20 ml of 5% aqueous sodium bicarbonate, and the ethyl acetate phase was retained after the separation.

The bicarbonate extracts were combined, layered with ethyl acetate, adjusted to pH 1.15 by addition of 2N HCl and saturated with sodium sulfate. The ethyl acetate was separated, and the aqueous phase was extracted with 2 x 30 ml of ethyl acetate.

All of the above ethyl acetate phases were combined, dried over sodium sulfate and evaporated to an oil, which was the free acid form of BL-P2013, and which was dissolved in approx. 20 ml of acetone, to which 20 ml of diethyl ether was then added. Then 50 percent potassium 2-ethylhexanoate (KEH) in dry n-butanol was added to a neutral state. The product 5 (BL-P2013) crystallized out. After stirring at 22°C, it was collected by filtration, whereby a yield of 650 mg of compound 5 (37% yield) was obtained.

A 50 mg sample of compound 5 was dissolved in 0.5 ml of water, and 20 mg of N,N<*->dibenzylethylenediamine (DBED) diacetate was added. The DBED salt of 5 uncrystallized was collected by filtration, washed with water and dried over P2O5 under vacuum to give N,N1-dibenzylethylenediamine-2-chloromethyl-2-methylpenam-3-carboxylate sulfone (the DBED salt of the free acid 5).

Another sample of 5 (450 mg) was dissolved in 3 ml of water to which was added a solution of 270 mg of DBED diacetate in 2 ml of water. During scraping, the DBED salt of 5 (430 mg) crystallized. Recrystallization from ca. 5 boiling acetate gave a yield of 270 mg.

Example 2

Pivaloyloxymethyl- 2B- chloromethyl- 2g- methylpenam- 3a- carboxylate- sulfone

(BL-P2024)

To a stirred suspension of 14.6 g (0.0487 mol) BL-P2013 (5) in 200 ml of acetone was added 4 ml of a 10 per cent aqueous solution of sodium iodide, and the mixture was cooled on a steam bath. To the suspension under reflux was added 14.8 ml (0.1 mol) of redistilled chloromethylpivalate (b.p. 34°C at 7 mm Hg) in one portion. The mixture was stirred under reflux for 3 hours and then cooled to room temperature (22°C). The crystalline solids were collected by filtration, washed with 3 x 30 mL of acetone, and the combined filtrates were evaporated in an oil under vacuum at below 22°C. The oil was then taken up in 500 ml of ethyl acetate and washed once with 200 ml of water and once with saturated Na 2 O 4 while stirring with 2 g of decolorizing carbon while cooling (ice bath). After 20 minutes, the mixture was filtered through a diatomaceous earth pad ("Dicalite") with suction, and the pad was washed with 4 x 100 ml of ethyl acetate. The combined filtrates were concentrated under vacuum at 22°C to an oil. The oil was then further concentrated at 22°C and < 1 mm Hg to remove most of the remaining chloromethy pivalate. The remaining oil was then treated twice with 50 ml portions of n-pentane and was stored over the weekend in a cold room (approx. 10°C) under n-heptane. The solid crystalline mass was then broken up to a solid powder with 40 ml of a 4:1 mixture of ether-n-pentane. The product was then collected by filtration, washed with ether-pentane (1:1), then pentane, after which it was air-dried. After drying under vacuum for four hours over P2O5, 13.37 g of pivaloyloxymethyl-2-chloromethyl-2-methylpenam-3-carboxylate-sulfone (ca. 75% yield) were obtained, m.p. 93-95°C.

Analysis calculated for C14<H2>QC<1>N07S:

C: 44.03; H: 5.27; N: 3.67.

Found: C: 44.11; H: 5.08; N: 3.85.

Example 3

Recrystallization of potassium- 2B- chloromethyl- 2a- methylpenam- 3a- carboxylate- sulfone ( BL- P2013)

To a mixture of 20 ml of n-butanol and 1 g of BL-P2013 (5), water was added, 1 ml at a time, while shaking in a separatory funnel until a pale yellow solution was obtained. The clear solution was filtered through a folding filter, and the flask and filter paper were washed with approx. 10 mL of 9:1 n-butanol-H 2 O, and the combined filtrates were diluted with an additional 20 mL of n-butanol. The resulting solution was placed in a round bottom flask on a rotary evaporator and evaporated under reduced pressure to approx. half of the original volume. The snow white crystalline product was collected by filtration, washed with 6 x 10 ml of acetone and air dried, yield 810 mg. After vacuum drying for 6 hours over P2°5 under ^ 111111 Hg, 800 mg were obtained, m.p. 215°C during cleavage (80% yield).

Analysis calculated for CgHgClN05SK.1H20:

C: 29.67; H: 3.39; N: 4.63; Cl: 10.94; K.F.H 2 O: 5.56, Found: C: 29.23; H: 3.38; N: 4.49; Cl: 10.74; K.F.H 2 O: 5.74.

This recrystallization process produces a crystalline monohydrate which is different from the starting material and which is largely anhydrous.

Example 4

As described in US Patent 3,860,579, 50 g (0.375 mol) of recrystallized phthalide and recrystallized N-bromosuccinimide (0.375 mol) were refluxed for 4.5 hours in the presence of approx. 100 mg of α-azobutyronitrile in 1 liter of CCl^ and filtered. The mixture was cooled to approx. 15°C and filtered to remove succinimide, which itself had been washed with approx. 100 ml of CC14 and filtered. The combined CCl4 ~ phases were concentrated under vacuum to approx. 150 ml, which gave

50 ml of CCl^ and air-dried, whereby 54 g of yield was obtained, which weighed 50 g after recrystallization from boiling cyclohexane, m.p. 84-86°C.

To a stirred partial solution and partial suspension of 2.3 g (0.0075 mol) of compound 5 in 20 ml of dimethylformamide (DMF, dried for at least 3 weeks over 3A° molecular sieves) was added 1.7 g (0.008 mol ) 3-bromophthalimide (12), and the mixture was stirred for 4 hours at 22°C. The resulting mixture was poured into a mixture of 200 ml of ice-cold water and 200 ml of ice-cold ethyl acetate (while rinsing the flask with a little ethyl acetate), and the mixture was shaken. Then the organic solvent phase was separated and washed with seven portions of ice-cold water (100 ml). The ethyl acetate phase was washed once with sat. B" (bp. 60-68°C, mainly n-hexane) (25 ml) and four times with 25 ml of n-hexane, whereby 2.5 g of compound 13 was obtained as a next white solid after drying in air. This product was then dried over P2°5 under 1 mm Hg to give 2.5 g of compound 13, m.p. 104°C during cleavage. Its purity was estimated at 85-95%.

Analysis calculated for C^gH^ClNOyS:

C: 51.61; H; 3.79, N: 3.77; Cl: 9.53,

Found: C: 52.59; H; 4.67; N: 3.21; Cl: 7.73,

K.F.H 2 O: 0.27.

Example 5

Pivaloyloxymethyl- 2B- chloromethyl- 2a- methylpenam- 3a- carboxylate- sulfone

A mixture of 1 g (0.0031 mol) of potassium 2e-chloromethyl-2a-methylpenam-3a-carboxylate sulfone hydrate and 1 g of 3A molecular sieves was stirred in 15 ml of dimethylacetamide for 2 hours at 23°C. To this mixture was added 470 mg (0.0031 mol) of pivaloyloxymethyl chloride, and stirring was continued for 18 hours. The molecular sieves were collected, and the filtrate was diluted with 100 ml of water and extracted with ethyl acetate. The ethyl acetate was washed nine times with water and dried over anhydrous magnesium sulfate. The solvent was removed at 30°C and 15 mm, leaving an oil which was chromatographed on silica using "silicar CC-7" (methylene chloride 8, ethyl acetate 2), as shown by a spot at Rf 0.5. The obtained residue was crystallized from heptane "(Skellysolve B"), whereby a yield of 100 mg (m.p. 94-95°C) pivaloyloxymethyl-2-chloromethyl-2-methylpenam-3-carboxylate sulfone was obtained.

Analysis calculated: C: 44.03; H: 5.27; N: 3.67,

Found: C: 44.20; H: 5.24; N: 3.63.

The NMR and IR spectra were consistent with the structure.

Example 6

Sodium- 2B- chloromethyl- 2a- methylpenam- 3a- carboxylate- sulfone

To a stirred solution of 500 mg of the potassium salt of BL-P2013 in 5 ml of water and 10 ml of ethyl acetate was added 2N HCl until the pH was reached (in an ice bath with vigorous stirring). The mixture was then saturated with Na 2 SO 4 , the aqueous layer was separated, and the organic phase was dried briefly in ice over Na 2 SO 4 , filtered and treated dropwise with 50 percent NaEH (sodium 2-ethyl hexanoate) in anhydrous n- butanol to neutral condition for moist pH paper. The product did not crystallize on scraping and was then concentrated under vacuum to an oil, which was dissolved in 5 ml of acetone, scraped - no crystals, ether was added to the cloud point - no crystals. It was concentrated under vacuum on a rotary evaporator to an oil, which was dissolved in ethyl acetate after which one drop of H 2 O was added, scraped - no crystals.

It was concentrated under vacuum and the residue treated with 5 ml of n-butanol to give 200 mg of amorphous white powder, which was washed with ether, air dried and vacuum dried over P 2 O 5 i 24 h. A final yield of 180 mg of sodium 2B-chloromethyl-2a-methylpenam-3a-carboxylate sulfone was obtained, which decomposed at above 100°C indeterminately.

Analysis calculated for CgHgClNO^SNa;

C: 33.10; H: 3.13; N: 4.89,

Found: C: 33.20; H: 3.69; N: 4.44; K.F.I^O: 4.04.

Example 7

Preparation of BL-P2013 free acid

To a mixture of 25 ml of ethyl acetate and 10 ml of water was added 800 mg (0.00261 mol) of BL-P2013 potassium salt. After all the solid had dissolved, the mixture was treated dropwise with 50 percent aqueous phosphoric acid with vigorous shaking until no more material precipitated from the aqueous layer. The ethyl acetate layer was separated, then washed with saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The desiccant was removed by filtration and washed with 10 ml of ethyl acetate. The washing liquid was combined with an original filtrate. "Skellysolve B" was then added to the ethyl acetate until the point of cloudiness (about 10 ml). The mixture was treated with 500 mg of active "Skellysolve B" and then seeded with crystals of BL-P2013 free acid. After approx. 3 hours at room temperature, the crystalline precipitate of free acid was collected and dried under vacuum (15 minutes) over P2°5'nvorve^ 323 mg (46%) were obtained, which was slowly decomposed over 100°C.

Analysis calculated for CgH10ClNO5S:

C: 35.89; H: 3.77; N: 5.23; Cl: 13.25

Found: C: 35.88; H; 3.91; N: 5.41; Cl: 13.52.

This product was found to be unstable when stored at 23°C for seven days.

Example 8

Pivaloyoloxymethyl- 2e- chloromethyl- 2- methylpenam- 3- carboxylate- sulfone

(BL-P2024)

4 ml of a 10% aqueous solution of sodium iodide, and the mixture was brought to reflux on a steam bath. To this suspension, which was refluxed, 14.8 ml (0.1 mol) of redistilled chloromethyl pivalate (b.p. 34°C at 7 mm Hg) was added in one portion. The mixture was stirred under reflux for 3 hours and then cooled to room temperature (22°C). The crystalline solids were collected by filtration, and washed with 3 x 30 mL of acetone, and the combined filtrates were evaporated to an oil under reduced pressure at below 22°C. The oil was then taken up in 500 ml of ethyl acetate and washed once with 200 ml of water and once with 200 ml of saturated Na 2 SO 4 solution. The solution was then dried briefly over Na 2 SO 4 while stirring with 2 g of decolorizing carbon while cooling (ice bath). After 20 minutes, the mixture was filtered through a Celite pad and the pad was washed with 4 x 100 mL of ethyl acetate. The combined filtrates were concentrated under reduced pressure at 22°C to an oil. The oil was then further concentrated at approx. 22°C and less than 1 mm Hg to remove most of the remaining chloromethyl pivalate. The remaining oil was then treated twice with 50 ml portions of n-pentane and was then stored over the weekend at approx. 10°C under n-pentane. The resulting solid crystalline mass was then broken up to a powder with 40 ml of a 4:1 mixture of diethyl ether-n-pentane. The product was collected by filtration, washed with diethyl ether-n-pentane (1:1), then n-pentane and air-dried. After drying under high vacuum for 4 hours over P2°5kle, 13.37 g (approx. 75%) of pivaloyloxymethyl-2B-chloromethyl-2-methylpenam-3-carboxylate-sulfone (BL-P2024), m.p. 93-95°C.

Purification of BL-P2024

About. 3 g of crude BL-P2024 (obtained as described above) was dissolved in 5 ml of ethyl acetate, applied to a 4.5 x 40 cm column of silica gel ("Mallinckrodt CC-7") and eluted with CH2Cl2-ethyl acetate in a 4:1 volume ratio . The fractions, which contained a single spot at Rf 0.84 (thin layer chromatography on silica gel plates with 4:1 CH 2 Cl 2 -ethyl acetate, 12~ detection) were combined and concentrated under reduced pressure to 1.38 g of a crystalline solid. A portion of this material (900 mg) was dissolved in 5 ml of ethyl acetate. The resulting solution was filtered, diluted almost to the cloud point with petroleum ether ("Skellysolve B") and then stored at room temperature for 3 days. The crystals that formed were collected by filtration, washed with petroleum ether and dried, whereby 560 mg were obtained, m.p. 100-101°C, purified BL-P2024.

Analysis calculated for C^^qCINO-jS:

C: 44.03; H: 5.27, N: 3.67,

Found: C: 44.11; H: 5.08; N: 3.85.

Example 9

Preparation of the amino salt of BL-P2013

1. The free acid of BL-P2013 (250 ml) dissolved in 20 ml of acetone-methanol at a ratio of 1:1 by volume was filtered to produce a clear solution. 2. Anhydrous ammonium solution was prepared by adding 1 ml of ammonium hydroxide (30 percent, reagent grade) to 10 ml of acetone-methanol (1:1 volume) solvent, and then 1 g of anhydrous magnesium sulfate was added to this solution with gentle stirring, and the mixture was filtered through filter paper. The filtrate was termed "anhydrous ammonium solution". 3. To the filtrate in step 1, 2 ml of "anhydrous ammonium solution" was gradually added and it was mixed well. 4. A 100 ml portion of diethyl ether was mixed with the mixture from step 3 to precipitate the ammonium salt of BL-P2013. 5. The white ammonium salt was isolated from the solvent and washed with 2 portions of 50 ml each of diethyl ether. 6. The isolated powder was dried at 35°C in a vacuum oven overnight.

7. Analysis data as follows:

Calculated %C: 33.7; H: 4.6; N: 9.8,

Found: C: 33.66; H: 4.63; N: 10.12; dry by KF. Microscopic examination: Crystalline substance.

Example 10

1. 50 mg of the free acid of BL-P2013 was dissolved in a mixture of acetone and methanol in the volume ratio 1:1. It was filtered to produce a clear solution. 2. Sodium 2-ethylhexanoate solution was prepared by dissolving 40 mg of sodium 2-ethylhexanoate in 10 ml of a mixture of acetone and methanol in a 1:1 volume ratio. 3. To the filtrate in step 1, 10 ml of the solution according to step 2 was added, and it was mixed well. 4. A 10 ml portion of diethyl ether was mixed with the mixture of step 3 to produce precipitation of sodium salt of BL-P2013. 5. The white salt was immersed in the diethyl ether for 1-2 hours and then isolated from the solvent and washed with three portions of 5 ml each of diethyl ether. 6. The isolated powder was dried at 30°C in a vacuum oven overnight.

Example 11

Recrystallization of BL-P2013

400 mg of BL-P2013 was dissolved in a minimal amount of a mixture of acetone and water in the volume ratio 1:1, and diluted with 10 ml of acetone, filtered and then diluted with acetone to approx. 25 ml, and scraped, and after 30 minutes the crystalline hydrate was collected by filtration, washed well with acetone, air dried and then vacuum dried at less than 1 mm Hg overnight. Yield 280 mg.

Analysis calculated for CgHgClNOSK<*>H20:

C: 29.67; H: 3.39; N: 4.63; Cl: 10.94; H 2 O: 5.55;

Found: C: 29.32; H: 3.32; N: 4.44; Cl: 11.31; H 2 O: 5.90.

Example 12

N,N'-dibenzylethylenediamine salt of BL-P2013

BL-P2013 + 1/2 N,N'-dibenzylethylenediamine diacetate

306 mg (0.001 mol) of BL-P2013 was dissolved in 7 ml of water and added to a solution of 180 mg (0.0005 mol) of N,N<1->dibenzylethylenediamine diacetate in 7 ml of water. The mixture was stirred, and the salt crystallized, and after stirring for approx. 10-15 minutes, the salt was collected by filtration and air dried to form 300 mg of the N,N<*->dibenzylethylenediamine salt of BL-P2013. The material was re-crystallized by solution for approx. 10 ml of boiling acetone and diluting with ether to the cloud point. 2 60 mg of air-dried and vacuum-dried material was obtained.

Analysis calculated:

C: 51.69; H; 5.42; N: 7.53; Cl: 9.55,

Found:

C: 49.39; H: 5.49; N: 7.05; Cl: 8.96; H 2 O: 1.23 (KF).

Example 13

Chloromethyl ester of BL- P2013

To a vigorously stirred mixture of 15.25 g (0.05 mol) BL-P2013 (5), 15 g (0.15 mol) KHCO 3 and 1.7 g (0.005 mol) tetra-butylammonium hydrogen sulfate in a mixture of 50 mL water and 50 ml of CH2Cl2, a solution of 9.5 g (0.575 mol) ClCH2-0-SO2Cl in 40 ml of CH2Cl2 was added dropwise. The temperature rose to 26°C, and after the addition, which took approx. 15 minutes, the mixture was stirred for an additional 30 minutes. Because the product crystallized, it was added with approx. 400 mL, CH 2 Cl 2 to produce a solution. The separated CH 2 Cl 2 layer and a 50 ml CH 2 Cl 2 wash were combined, dried over MgSO 4 with stirring, and 2 g of decolorizing carbon ("Darco KB") was added. After approx. 30 minutes, the mixture was filtered and concentrated to approx. 50 ml, and 150 ml of isopropyl alcohol was added. Then the rest of the CH 2 Cl 2 was removed under reduced pressure. The resulting crystalline precipitate was collected by filtration, washed well with isopropyl alcohol and air-dried. After vacuum drying at less than 1 mm Hg, 8.5 g of chloromethyl-26-chloromethyl-2-methylpenam-3-carboxylate sulfone (7) was obtained, m.p. 116°C during decomposition, turns dark above 100°C.

Analysis calculated for C9H11C<1>2N<0>5<S:>

C: 34.18; H: 3.51; N: 4.43; Cl: 22.43,

Found: C: 34.16; H: 3.45, N: 4.47; Cl: 22.46, H2O: 0.33 (KF)

Iodomethyl ester of BL-P2013

Iodomethyl ester of BL-P2013

To a stirred mixture of 5 g (0.0159 mol) of chloromethyl ester of BL-P2013 (7) in 25 ml of acetone was added 3 g (0.02 mol) of sodium iodide. The resulting slurry was stirred for 17 hours and then cooled to approx. 0°C. Two drops of saturated aqueous KHCO 3 were added and the mixture was slowly diluted dropwise with water over 10 minutes until 50 ml had been added. The slurry underwent a sudden color change from yellow to gray to violet to black and the crystals were therefore immediately collected by filtration and washed with cold acetone water (1:2) then with isopropyl alcohol (3 x 10 mL), then diethyl ether and finally with n -pentane, and air-dried, whereby a yield of 5.55 g (91% yield) of the iodomethyl ester of BL-P2013 (8) was obtained. Temp. 118-119°C during cleavage. The purity was estimated at approx. 90%.

Biological data

The product from example 1 with the formula

will hereafter be referred to as BL-P2013.

Although BL-P2013 is at best a very weak antibacterial by itself, it inhibits 6-lactamases and protects ceforanid and amoxicillin from destruction of B-lactamase-producing bacteria in vitro and in vivo when used in combination with these two agents .

The compounds in question are thus valuable, administered orally and parenterally, for improving the effectiveness of B-lactam antibiotics against 8-lactamase-producing bacteria. On a weight basis, the dosage is from 1/5 to 5 times, preferably

equal to the dosage of the B-lactam antibiotic. E.g. the compounds in question as shown above used in a 1:1 ratio markedly improved the activity of ceforanid and amoxicillin against 8-lactamase-producing strains of anaerobic bacteroides, such as B. fragilis, B. thetaiotaomicron and other species of this genus

and also against resistant Staphylococcus aureus. The compounds in question are administered either in mixture with or simultaneously with the 6-lactam antibiotic at a dose within the indicated ratio together with the known or usual dose of the antibiotic.

Thus, the ability of the compounds to increase the effectiveness of a B-lactam antibiotic against certain B-lactamase-producing bacteria makes them valuable for administration with certain B-lactam antibiotics for the treatment of bacterial infections

in humans and mammals. When treating a bacterial infection, a compound according to the invention can be mixed with the B-lactam antibiotic, and the two agents are thereby administered simultaneously. Alternatively, a compound according to the invention can be administered as a separate agent during a course of treatment with a B-lactam antibiotic.

When a compound according to the invention or a salt thereof is used to increase the antibacterial activity of a B-lactam antibiotic, it can be administered alone or preferably formulated with standard pharmaceutical carriers and diluents. A compound according to the invention which is in acid form or as a pharmaceutically acceptable salt thereof,

can be administered orally or parenterally. A compound according to the invention in the form of an ester, which is easily hydrolysable in vivo, is best administered orally. Parenteral administration includes intramuscular, subcutaneous, intraperitoneal and intravenous administration.

When a compound according to the invention is used in the presence

of a carrier or diluent, the carrier or diluent is selected on the basis of the intended mode of administration. When administered orally, the compound can e.g. used in the form of tablets, capsules, lozenges, lozenges, powders, syrups, elixirs, aqueous solutions and suspensions and the like,

in accordance with standard pharmaceutical practice. The ratio between active ingredients and carrier will of course depend on the chemical nature, solubility, stability and strength of the active ingredients as well as on the intended dose. However, these pharmaceutical preparations are likely to contain from 5 to 8% of carrier. In the case of tablets for oral use, commonly used carriers include lactose, sodium citrate and salts of phosphoric acid. Various disintegrants, such as starch, and lubricants, such as magnesium stearate, sodium lauryl sulfate and talc, are commonly used in tablets. Valuable diluents for oral administration in capsule form are lactose and high molecular weight polyethylene glycols. For aqueous suspensions for oral use, the active ingredients are combined with emulsifying and suspending agents. If desired, certain sweetening or flavoring substances can be added. For parenteral administration, which includes intramuscular, intraperitoneal, subcutaneous and intravenous use, sterile solutions of the active ingredients are usually prepared, and the pH of the solution is adjusted appropriately and buffered. For intravenous use, the total concentration of dissolved substances should be controlled so that the preparation becomes isotonic.

Although the prescribing doctor ultimately determines the dose to be used for a human individual, the ratio of the daily doses between a compound according to the invention or a salt thereof and the B-lactam antibiotic will usually lie in the range from 1:5 to 5: 1, preferably approx. 1:1. Moreover, the daily dose of each component will usually lie in the range from 10 to 200 mg per kg body weight, and the daily parenteral dose of each component will usually be from 10 to 100 mg per kg body weight. These figures only serve to illustrate the invention, and it may in some cases be necessary to use doses outside these limits.

Claims (1)

Process for the preparation of a 2ø-chloromethyl-2a-methyl penam-3<x-carboxylic acid sulfone of the formula a pharmaceutically acceptable salt of the acid or a physiologically hydrolyzable ester of the acid, characterized in that in order a) oxidises, such as with KMnO 2 , H 2 O 2 or a similar peroxide or a peracid, an ester of the formula to produce a sulfone of the formula and then b) reacting the sulfone with a metal in acid, such as with zinc in glacial acetic acid, to produce the desired acid or salt, and then if desired c) esterify the acid or its salt to form a physiologically hydrolyzable ester of the acid.