NO164300B - P-NITROBENZYL-6ALFA-BROMO-2BETA-CHLOROMETHYL-2ALFA-METHYL-PENAMAR CARBOXYLATE AND PROCEDURES FOR PREPARING THEREOF. - Google Patents

Description

The present invention relates to an intermediate for use in the preparation of 2B-chloromethyl-2a-methylpenam-36-carboxylic acid sulfone, a pharmaceutically acceptable salt or an easily hydrolyzable ester thereof, which is valuable as an inhibitor of B-lactamases.

The invention also relates to a method for producing it.

The presumed connection between the resistance shown by certain bacteria to B-lactam antibiotics and the ability of such bacteria to produce 6-lactamases has led to an intense search for 8-lactamase inhibitors. Clavulanic acid is an example of such a compound that is currently being studied extensively. Another ε-lactamase inhibitor has the structure in acid form and is known from European patent application 2927, published on 11 July 1969. The connection with the structure is known from US patents 4,036,847, 4,009,159, 3,993,646, 3,989,685 as well as 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. Also Farmdoc Abstracts 82090A, 1033B and 443337B. ' <■ The connection (under the number CP-45899) with the structure

is an irreversible 6-lactamase inhibitor with excellent solution stability. It has weak antibacterial activity and enhances the in vitro and in vivo activities of ampicillin against β-lactamase-producing strains. [ Y.R. English et al., Antimicrobial Agents and Chemotherapy, Vol 14, pp. 414-419, Aswapokee et al., J. Antibiotics, Vol 31(12), Dec. 1978, p. 1238-1244 as well as Derwent's Farmdoc Abstracts 89627A and 73866B].

B. Baltzer et al have in Mutual Pro-Drugs of B-Lactam Antibiotics and B-Lactamase Inhibitors, J. Antibiotics, Vol 33(10), 1980, p. 1183-1192 described that the principle of combining a 6-lactam antibiotic with a B-lactamase inhibitor in a single molecule, which functions as a pro-drug for the two active components, is illustrated by the bound esters 3 and 4, where respectively ampicillin and mecillinam are combined with the B-lactamase inhibitor penicillin-lan -sulfone. It has been shown that these esters in humans are absorbed excellently from the gastrointestinal tract and after absorption are hydrolysed with simultaneous release of the active components. As a result of this, high blood level and tissue values of antibiotic and iso-lactamase inhibitor are achieved in a balanced ratio. The advantages of "reciprocal pro-drugs" over simple combinations are discussed.

The esters 3 and 4 mentioned there have the structures

GB patent document 2,044,255 relates to hitherto unknown compounds with the general formula 1:

where 1^ is a phenyl, 4-hydroxyphenyl, 1,4-cyclohexadienyl or a 3-thienyl group, R- is a primary amino group or a carboxy group, R is a hydrogen atom or a lower alkyl, aryl or aralkyl radical , and A is a radical of a B-lactamase inhibitor that contains both a B-lactam ring and a carboxy group, and where A is bound via the carboxy group.

These new compounds are valuable for the treatment of bacterial infections and are particularly highly active against 8-lactamase-producing bacteria. See also Fardoc Abstracts 60773C and 60776C.

The compound according to the invention is characterized by having the formula

The method for producing the compound is characterized by heating a compound with the formula in an inert, anhydrous, organic solvent in the presence of large, preferably equimolar, amounts of a weak tertiary amine and an acid chloride until the reaction is largely complete.

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

Example 1

6 g- bromopenicillanic acid- S- sulphoxide ( 1)

1. 30 g (37.5 mmol) 6α-bromopenicillanic acid-N,N<1->dibenzyl-ethylenediamine salt [G. Cignarella et al., J. Org. Chem. Vol 27, 1962, p. 2668 and E. Evrard, Nature, Vol 201, 1964, p. 1124 ] is dissolved in 330 ml of methylene chloride. It is stirred and cooled to 0°C. 2. 13 ml (156 mmol) of concentrated hydrochloric acid is slowly added to the methylene chloride solution. Precipitation of the dibenzylethylenediamine-HCl salt (DBED"HC1 occurs within one minute. The slurry is stirred at 0-5°C for 10 minutes. 3. The precipitate of DBED"HC1 is filtered through a pre-coated diatomaceous earth filter ("Dicalite") . The filter cake is washed with 150 ml of methylene chloride. The filtration should end as soon as possible. One should avoid storing the acidic methylene chloride solution for a longer period of time. There may be some filtration problems due to the fine nature of the precipitate. Addition of a filtration aid to the slurry may be necessary help. 4. The mixture of methylene chloride filtrate and washing liquid is washed with 60 ml of cold water. It is stirred for 5 minutes, and the aqueous phase is discarded. The pH value of the washing liquid is 2.0-2.3. 5. The methylene chloride solution, which contains 6a-bromopenicillanic acid , is concentrated under reduced pressure to a volume of 65-80 ml. The solution is cooled and stirred to 5° C. 6. With vigorous stirring, carefully add 13 ml (86.9 mmol) of 40 percent peracetic acid over a period of 30 minutes. The reaction is exothermic. The temperature is kept between 15 and 18°C with ice bath cooling. The sulphoxide begins to crystallize after 10 ml of peracid has been added. The slurry is cooled and stirred at 0-5°C for 2 hours. 7. It is filtered and the snow-white filter cake is washed with 10 ml of 5°C water, then with 10 ml of 0-5°C methylene chloride and finally with 15 ml of heptane. 8. The filter cake is dried in an air oven at 45°C to a constant weight, whereby 6-10 hours should be sufficient. Excessive heating may develop traces of a pinkish color. The weight of 1 is approx. 16.26 g, yield 73.24%. 9. The reaction mixture and the final product can be analyzed by thin-layer chromatography using solvent systems consisting of 15 parts toluene/4 parts acetone/1 part acetic acid (HAC) or 8 parts acetone/8 parts methanol/3 parts toluene/1 part HAC. The final product is analyzed by NMR and IR.

p- nitrobenzyl- 6g- bromopenicillanate- S- sulfoxide ( 2)

To a solution of 12 g (0.04 mol) of 6α-bromopenicillanic acid S-sulfoxide in 100 ml of acetone was added 7.5 g (0.041 mol) of potassium 2-ethylhexanoate. The salt was collected by filtration, washed with cold acetone and air dried to a total yield of 10 g. The crystalline potassium salt was dissolved in 75 ml of dimethylacetamide and 7.8 g (0.04 mol) of p-nitrobenzyl bromide was added. The solution was stirred at 23°C for 24 hours. The mixture was diluted with 500 ml of water and extracted with ethyl acetate. The ethyl acetate layer was washed four times with water and dried over anhydrous magnesium sulfate. The solvent was evaporated at 35°C (15 mm) to an oil, which crystallized. The pale golden brown crystals of 2 were slurried with ether and collected by filtration in a yield of 9 g (70%), m.p. 124-125°C during cleavage.

Analysis calculated for C15H15BrN2OgS:

C: 41.98, H: 3.05, N: 6.52

Found: C: 42.00, H: 3.48, N: 6.98.

IR(KBr): 1800(s), 1740(s), 1610(w), 1520(s), 1450(ra), 1350 (s), 1060(m), 740(m) cm"<1>. H-NMR (60 mHz, DMSO) : δ 1.22 (s,3H), 1.6 (S,3H), 4.67 (s,1H), 5.2 (d,J~1-5 Hz , 1H), 5.45 (s,2H), 5.68 (d,J~1-5 Hz, 1H), 7.5-8.5 (ra,4H).

p-nitrobenzyl-2B-chloromethyl-2a-methyl-6-bromopenam-3a-carboxylate

(3)

A solution of 5 g (0.012 mol) of p-nitrobenzyl-6a-bromopenicillanate-S-sulfoxide (2) in 120 g of anhydrous dioxane was heated under reflux under nitrogen for 4 h with 1.5 g (0.012 mol) of quinoline and 1.6 g (0.012 mol) benzoyl chloride. The solution was diluted with 600 ml of water and extracted with ethyl acetate. The ethyl acetate extract was washed with 5 percent sodium bicarbonate solution, 5 percent phosphoric acid solution and finally with water. The organic layer was dried over anhydrous magnesium sulfate and evaporated to an oil at 35°C (15 mm). The oil crystallized and was collected, washed with ether and finally with cold toluene to yield 3 in 3.5 g (65%), m.p. 130-135°C during cleavage.

Analysis calculated for C15H15<C>lBrN205S:

C: 40.06, H: 3.14, N: 6.23,

Found: C: 40.19 H: 3.12, N: 6.75.

IR(KBr): 1792(s), 1740(s), 1610(w), 1520(s), 1353(s), 1280 (m), 1025(w), 990(w), 750(w) cm "<1>. NMR (60mHz, DMSO): δ 1.45 (s,3H), 3.5-4.3 (M,2H), 5.05 (s,1H), 5.42 (s, 2H), 5.5 (d,J~1.5 Hz,1H), 5.62 (d,J~1.5 Hz,1H), 7.5-8.5 (m,4H).

Example 2

a) 6 a- bromopenicillanic acid sulfoxide

To 3 liters of methylene chloride was added 300 g (0.75 mol)

6α-bromopenicillanic acid-N,N'-dibenzylethylenediamine salt, and this suspension was cooled to 5°C. 130 ml of concentrated HC1 were then added dropwise over the course of 15 minutes and with good stirring. The slurry was stirred at 5°C for 2 hours. It was then filtered through a pad of diatomaceous earth ("Celite") and the cake was washed with 3 x 250 ml of methylene chloride.

The combined methylene chloride solutions were washed with 2 x 500 mL water and dried over sodium sulfate for 15 minutes. The sodium sulfate was removed by filtration, and the filtrate was evaporated under reduced pressure to approx. 750 ml.

This solution was cooled to 5°C, and with vigorous stirring 130 ml of 40 percent peracetic acid was added dropwise, so that the temperature was kept at 5-12°C. The addition was fairly exothermic. After the addition was complete, the slurry was stirred at 5°C for 2 hours, and the product was collected by filtration and washed with 100 ml of cold water (5°C) and 100 ml of cold methylene chloride (5°C). 126 g (57%) of 6α-bromopenicillanic acid sulfoxide were obtained, m.p. 129°C. The IR and NMR spectra were consistent with the desired product.

Analysis calculated for CgH^0BrNO4S:

C: 32.44, H: 3.40, N: 4.73,

Found: C: 32.30, H: 3.35, N: 4.71, H 2 O: 2.18.

b) Potassium 6a- bromopenicil Ianat sulphoxide

To 3 liters of acetone were added 126 g (0.43 mol) of 6a-bromopenicillanic acid sulfoxide and 162 ml of 50% by weight potassium 2-ethylhexanoic acid in n-butanol. After stirring for 1 hour at 22°C, the product was collected by filtration, washed with 2 x 250 ml of acetone and dried. 127 g (90%) of potassium 6a-bromopenicillanate sulfoxide were obtained, m.p. 185°C. The IR and NMR spectra were consistent with the desired product.

Analysis calculated for CgHgBrKN04S:

C: 28.75, H: 2.71, N: 4.19,

Found: C: 29.03, H: 2.78, N: 4.04.

c), p-nitrobenzyl-6a-bromopenicillanate sulfoxide

To 1 liter of N,N-dimethylacetamide was added 145 g (0.43

mol) potassium 6a-bromopenicillanate sulfoxide, and with stirring 115 g (0.53 mol) of p-nitrobenzyl bromide were added at 22°C. The mixture was stirred at 22°C for 20 hours.

The reaction mixture was poured into 3 liters of water and extracted with 3 x 1500 ml of ethyl acetate. The combined ethyl acetate extracts were washed with 2 x 500 ml of 5% aqueous sodium bicarbonate solution and dried over sodium sulfate for 1 hour. The sodium sulfate was filtered off, and the filtrate was evaporated under reduced pressure to a residue, to which 1 liter of diethyl ether was added, which caused crystallization of the product. The crystals were collected, collected by filtration, washed with 2 x 100 ml of diethyl ether and dried to yield 162 g (87%) of p-nitrobenzyl-6o-bromopenicillanate sulfoxide, m.p. 111°C. The IR and NMR spectra were consistent with the structure of the desired product.

Analysis calculated for C-^H^gBrt^OgS:

C: 41.78, H: 3.51, N: 6.50,

Found: C: 41.66, H: 3.45, N: 6.85, H 2 O: 0.69.

d) p- nitrobenzyl- 6a- bromo- 26- chloromethyl- 2- methyl penam- 3- carboxylate

To 1 liter of p-dioxane was added 70 g (0.16 mol) of p-nitrobenzyl-6a-bromopenicillanate sulfoxide, followed by 21.2 ml (0.10 mol) of benzoyl chloride and 21.8 ml (0.19 mol ) quinoline. The reaction mixture was refluxed for 4 hours and then cooled to 22°C, poured into 2500 ml of water and extracted into 3 x 800 ml of ethyl acetate. The combined ethyl acetate extracts were washed with 300 ml of 5% aqueous sodium bicarbonate solution, 300 ml of 5% aqueous phosphoric acid and 300 ml of water. The ethyl acetate solution was dried over sodium sulfate for 1 hour, and the sodium sulfate was removed by filtration. The filtrate was evaporated under reduced pressure to a residue which was dissolved again in 1 liter of ethyl acetate and again evaporated under reduced pressure to a residue. Then 1 liter of diethyl ether was added, and the product was collected by filtration in a yield of 41 g (57%) of p-nitrobenzyl-6a-bromo-2e-chloromethyl-2-methylpenam-3-carboxylate, m.p. 132°C. The IR and NMR spectra were consistent with the desired structure.

Analysis calculated for C^H^BrCll^C^S:

C: 40.06, H: 3.14, N: 6.23,

Found: C: 40.62, H: 3.11, N: 6.13.

Reference is also made to Norwegian patent application 810166 and Norwegian patent application 853450 from which the present application is divided.

Claims (2)

1. New compound, characterized in that it has the formula 2. Process for producing the compound according to claim 1, characterized in that a compound with the formula is heated in an inert, anhydrous, organic solvent in the presence of large, preferably equimolar, amounts of a weak tertiary amine and an acid chloride until the reaction is substantially complete.