DK145629B - METHOD OF PREPARING CEPHALEXIN OR HEETACEPHALEXIN OR SALTS THEREOF - Google Patents

Description

(19) DENMARK (HH

(12) SUBMISSION WRITING (tu 1 ^ 5629 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 1677/71 (51) Int.CI.3 C 07 D 501/58 (22) Filing date 7 · Apr. 1971 C 0 / D 501/10 (24) Race day 7 · Apr. 1971 (41) Aim. available 11. October 1971 (44) Posted 3 Jan. 198? (86) International application # - (86) International filing day (85) Continuation day - (62) Master application no -

(30) Priority 10 Apr 1970, 27 ^ 41, US 5 · Oct. 1970, 78165 * US

(71) Applicant BRISTOL-MYERS COMPANY * New York * US.

(72) Inventor William Joseph Gottstein * US: Lee Cannon Cheney * US.

(74) Clerk Th. Os tenf eld Patenthureau A / s.

(54) Process for the preparation of cephalexin or hetacephalexin or salts thereof.

The present invention relates to a particular process for the preparation of cephalexin of the formula

/ ΓΧ- 0 "- S - HH η-fS

\ = / 1¾ 0J – 01I3

B. In C00H

r> si q or hetacephalexin of the formula in _ 0 / T \ 11 ^ s'

* // \ V_ CH - C - N --S N

\ = / NH / X-il X- CH, \ / o ^ T 3

1 c C00H

• CH3VCH3. II-2 145629 or a non-toxic, pharmaceutically acceptable salt thereof.

Cephalexin is a known antibacterial active compound derived from 7-desacetoxycephalosporanoic acid (7-ADCA), and as, e.g. are described in J. Med. Chem. 12, 310-313 (1969), British Patent Specification No. 1,174,335, South African Patent Specification No. 67/1260 (Farmdoc 28, 654), Japanese Patent Specification No. 16871/66 (Farmdoc 23231), and in Belgian Patent Specification No. 696,026 (Farmdoc 29494).

Hetacephalexin is a novel antibacterial active compound having the chemical name 7- (2,2-dimethyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid. The physical and biological properties of hetacephalexin are shown in Example 10.

Conversion of a penicillin sulfoxide ester (by heating in the presence of a strong acid) to the corresponding ester of a corresponding N-acylated derivative of 7-ADCA is disclosed in the description to U.S.A. Patent Nos. 3,275,626 and in J. Ammer.Chem.Soc., 85, 1896 (1963) and 91 (6), 1401-1407 (1969). Variants of this method are disclosed in Dutch Patent Specification 68/06532 (Farmdoc 34,685) and Dutch Patent Specification No. 68/06533 (Farmdoc 34,686). These patents generally refer to the side chain of a fermentable penicillin, such as penicillin G or V (see, however, column 7 of U.S. Patent No. 3,275,626), and the product is an ester to be cleaved, such as by hydrogenation, to preparation of the active free acid form of the finished derivative of 7-ADCA. British Patent Specification No. 1,174,335 discloses in Example 3 the use of this "sulfoxide rearrangement" on an ester of ampicillin sulphoxide in which the α-amino group is also blocked, namely 6- / N- (2,2,2-trichloroethylcarbonyl-Da). amino-α-phenylacetamido / penicilianic acid sulfoxide-2,2,2-trichloroethyl ester, by heating and subsequent use of zinc and acetic acid to remove the two blocking groups and thus produce cephalexin.

The prior art contains numerous further descriptions of penicillin sulfoxides and their preparation, e.g. described by Chow et al., J. Org.Chem. 27, 1381 (1962), by Guddal et al., Tetrahedron Letters No. 9, 381 (1962), by Essery et al., J. Org.Chem. 30, 4388 (1965), which includes ampicillin sulfoxide, and in the disclosure to U.S.A. Patent No. 3,197,466.

The reaction product between acetone and cephaloglycine, but not cephalexin, is described in U.S.A. Patent Specification No. 3,303,193. The reaction between acetone and certain ring-substituted cephalexin derivatives is generally described in U.S.A. U.S. Patent Nos. 3,489,750, 3,489,751, and 3,489,752.

The disadvantages of the known methods of use in the preparation of cephalexin are, inter alia, in the necessity of carrying out a series of reactions to replace the original side chain when using as a starting material a fermented penicillin, e.g. penicillin V, and the necessity, when starting with the desired side chain (α-amino-benzyl), to first introduce and later remove blocking groups for both the α-amino group and the carboxyl group.

The present invention makes use as a starting material of hetacillin, which is a well-known antibacterial agent, derived from 6-amino-penicillanic acid (6-APA), and as e.g. are described in U.S.A. U.S. Patent No. 3,198,804 and J. Org. Chem. 31, 897 (1966). Thus, hetacillin already contains the desired side chain, and the process of the invention is based on the surprising realization that the 3-imino group in hetacillin can be readily blocked by a nitroso or formyl group, that the compound formed can then be readily oxidized to a sulfoxide intermediate which has unexpectedly proved to be reasonably well yielded in free acid form to the corresponding cephalosporin intermediate, which then, upon cleavage of the amino-blocking group, readily yields hetacephalexin, if desired followed by hydrolysis to form cephalexin. Thus, while all prior art indicates that relocation of a free acid form sulfoxide intermediate to a cepha-losporin intermediate causes decarboxylation of the free acid group, it has unexpectedly been found that such decarboxylation is substantially avoided by the 3-imino-blocking nitroso or formyl group in the present sulfoxide intermediate, and therefore the disadvantages of the prior art can be completely avoided by first blocking the A-amino group and the carboxylic acid group and then blocking them again. However, the process of the invention is not limited to rearrangement of the sulfoxide intermediate in free acid form, but is also feasible after blocking of the carboxyl group.

Thus, the process of the present invention is characterized by the following consecutive steps: A) blocking the 3-imino group in hetacillin of formula 4 145629 / "V-L λ \ z = / i-h-ι-r f

| CHO J-N-1- COOH

CH3

III

by nitrosation or formylation to give an intermediate of the formula

and CH

11 · c / 3 i N --- r y— 0113

- ^ CII -.N - 1- C00K

o, s V

Wherein Z represents nitroso or formyl, B) oxidizing the above-mentioned intermediate or a salt thereof to produce a sulfoxide intermediate of the formula: ao 0 "% / ° ¾ CH- C \ / v / n I - S y ~ CH3 & -N-

I 'CH0 Jr-ti-1- COOH

ch3 30 ^

V

or a salt thereof, and, if desired, blocking the carboxylic acid group of the above-mentioned sulfoxide in a manner known per se to produce a sulfoxide intermediate of the formula

Of-C -, - (V-3

w z-N - οςΗ3 1_1-L COOB

ch3 0

WE

Wherein COOB represents a protected carboxyl group and Z has the meaning given above.

C) heating the above-mentioned sulfoxide intermediate V or VI in an inert organic solvent in the presence of an acid catalyst to produce a cephalosporin intermediate of the formula a o in CH - q I N ---- {S '\

S5-H - I I

£ ** 3 * - ΚΑ

Ui3 o ci ^

X

WE YOU

wherein Z is as defined above, and X represents COOH or COOB or a salt thereof, and, if necessary, removal of the carboxyl protecting group in a manner known per se, and D) cleavage of the imino-blocking group to produce of hetacephalexin of the formula N— 'HH / Λ- ^ \ / O CHq

CH3 ^ CH3 COOH

II

or a non-toxic, pharmaceutically acceptable salt thereof and, if desired, hydrolyzing the above-mentioned compound to produce cephalexin of the formula?

(Ί— CH— C - KH - S N

NHg o <^ '~ -CH3

In COOH

or a non-toxic, pharmaceutically acceptable salt thereof.

The nontoxic, pharmaceutically acceptable salts include, e.g. (1) nontoxic, pharmaceutically acceptable salts of the acidic carboxylic acid group such as sodium, potassium, calcium, aluminum and ammonium salts and nontoxic substituted ammonium salts with amines such as t ri (lower) alkyl amines, procaine , dibenzylamine, N-benzyl / S-phenethylamine, 1-ephenamine, NjN'-dibenzylethylenediamine, dehydroabiethylamine, N, N'-bis-dehydroabiethylethylenediamine, N- (lower) alkylpiperidines such as N-ethylpiperidines and others amines used to form benzylpenicillin salts, and (2) non-toxic, pharmaceutically acceptable acid addition salts (i.e., salts of basic nitrogen) such as (a) mineral acid addition salts such as hydrochloride, hydrobromide, hydroiodide, sulfate, sulfamate , (sulfonate or phosphate), and (b) organic acid addition salts such as maleate, acetate, citrate, tartrate, oxalate, succinate, benzoate, fumarate, malate, mandelate, ascorbate, β-naphthalenesulfonate, and p-toluenesulfonate. Cephalexin can also exist as the "free acid", which naturally exists as a zwitter ion.

In reaction step (A), the 3-imino group of the hetacillin starting material is protected in the subsequent reaction steps by nitrosation and formylation. A preferred nitrosation method involves acidification to a pH of approx. 2 of an aqueous suspension of hetacillin with hydrochloric or dilute phosphoric acid until a solution is obtained, cooling the solution to ca. 10 ° C and then the addition of sodium nitrite in small portions with stirring to give N-nitroso-hetacillin. N-formylhetacillin may e.g. is prepared by reaction of formic acid and hetacillin.

The imino-protected hetacillin or a salt thereof is oxidized in known ways, e.g. in the manner described by Chow, Hall and Hoover in J.Org.Chem., 27, 1381 (1962) to form the corresponding sulfur oxide V. The hetacillin is reacted with the oxidizing agent in such an amount that at least one atom is actively oxygen is present per atom thia- 145629 zolidine syovl. Suitable oxidizing agents include, e.g. sodium metaperiodate, hydrogen peroxide, peracetic acid, monoperphthaisic acid and m-chloroperbenzoic acid. The best results are obtained when sodium metiodate is used as an oxidizing agent at a pH below 5. The reaction mixture is maintained at a pH below 5 to prevent or at least reduce the C-6 epimerization.

The conversion of N-nitrosohetacillin sulfoxide or N-formyl hetacillin sulfoxide to N-nitrosoheta-Cephalexin or .N-formylheta-cephalexin can be accomplished in various ways. Thus, the carboxyl group can first be blocked (in a manner that facilitates later removal, for example, with a silyl group (from dichlorodimethylsilane or the like) or as a mixed anhydride, for example from acetyl chloride. However, it was quite surprising that the conversion was very efficient without any blocking group at all on the carboxyl group, and in fact it is preferred to carry out the rearrangement step (C) with the free acid.

The sulfoxide intermediate obtained according to step (B) is converted to the corresponding cephalosporin intermediate by heating to elevated temperatures in the presence of an acid catalyst. Examples of suitable acid catalysts are sulfuric acid, phosphoric acid and other mineral acids, p-toluenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acids and other sulfonic acids and acetic anhydride, propionic anhydride or benzoic anhydride.

Any organic liquid can be used as the reaction medium in the rearrangement step, provided it is substantially inert to the other reactants under the conditions used. Preferred solvents are acetic anhydride and tetramethylurea, and the most preferred solvent is tetramethylurea. The reaction temperature should be in the range of approx. 100 to 140 ° C, most preferably from ca. 120 to 140 ° C. The reaction time should be kept as short as possible to prevent the formation of unwanted by-products. The best results have been obtained when the reaction has been carried out for a period of approx. 30 minutes to approx. 120 minutes.

At the end of the rearrangement step, lee. any carb-oxyl protecting group is removed in the usual manner, e.g. by hydrolysis, to form N-nitrosohetacephalexin or N-formylheta-cephalexin. The 3-imino-blocking nitroso or formyl group is then cleaved by acid hydrolysis, e.g. dry HCl in dioxane, catalytic hydrogenation, e.g. H2 over Raney nickel, or reduction with zinc and acetic acid to form hetacephalexin (II). Hetacephalexin can, if desired, be converted to cephalexin by acid or base hydrolysis. When it is desired to prepare hetacephalexin, the most preferred cleavage method involves the use of dry HCl, e.g. HCl in dioxane to make hydrolysis to cephalexin as low as possible.

The process according to the invention is illustrated in more detail in the following examples, where all temperatures are in ° C. "Dissolving Solve B" is a petroleum ether fraction having a boiling point of 60-68 ° C and consisting essentially of n-hexane.

Example 1

PhCH-co HN .N-CH— Clf ^ CMe, ----- 11 i

Me, OC-N-CHCO 3 H

Ph CH-CO

• ONN '.N-CH-CH CMe,

Cx I I I

Me, OC N-CHCOJH

2

ISLAND

PhCH-CO f I I i *.

ONN-CH-CH CMe, —- c II I Δ

Mc, OC-N-CHCO 2 H

3

Ph CH-CO

I I in HCl

ONN N-CH-CH CH, - II I 1 NaHCO.

Me, OC — Ν '^ CMe

'I

COlH

4

Ph CH-CO

I I H.

HN. N-CH-CH CH, JL

^ I 1 Ί HtO

Me, OC-N '> JCMe CO, Na 5

PhCHCONH-CH-CH CH,

I III

NH, OC-Nn ^ CMe

C

Ί

C0, H

A) 6 $ - (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid (2).

To a suspension of 142 g (0.37 mole) of commercial hetacillin (1) in 2 L of water at room temperature was added 69 g (0.41 mole) of sodium nitrite. The mixture was layered with 1.5 L of ethyl acetate and, with vigorous stirring, 6N hydrochloric acid was added dropwise until both layers were clear (pH of aqueous layer 1.9). The addition took 15 min. Stirring was continued for a further 15 minutes and the ethyl acetate was separated, washed with water and evaporated at 40 ° (15 mm). The crystalline solid was collected, washed with ether and recrystallized from methanol-water to give 110 g (71¾): m.p. 195 ° C dec.

Analysis calculated for C C ^H ^ ^N₂O₂S: C, 54.54; H, 5.30; N, 13.39. Found: C, 54.44; H, 5.5 S, N, 13.33.

B) 6β- (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide (3)

To a mixture of 110 g (0.263 mol) of 6 $ - (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid (2) in 2.5 L of water was added vigorous stirring 66 g (0.31 mole) of sodium metaperiodate. The solution was adjusted to pH 5 with 10¾ sodium hydroxide and the mixture was stirred at room temperature for 3 hours with periodic adjustment of the pH. Once the mixture had become clear, the solution was stirred for an additional 1 hour. The final pH of this solution was 4.1. The sulfoxide was precipitated by the addition of 40¾H ^PO ^ to a pH value 2, collected, washed thoroughly with water, air dried to constant weight, and finally dried in vacuo over P₂O5 to give 103g (91¾) of white crystals. An analytical sample was obtained by recrystallization from dimethylformamide and water: m.p. 160 ° C slow cover.

Analysis calculated for cigH22N4 ° 6S: c> 52.52; H, 5.11; N, 12.92 Found: C, 52.66; H, 5.37; N, 13.45.

C) β- (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid (4)

A stirred solution of 10 g (0.022 mol) of 6β- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide, monohydrate (3) and 2.5 g of anhydrous p -toluenesulfonic acid (prepared by aze-trop drying the monohydrate with ethyl acetate) in 250 ml of tetramethylurine substance was heated in a preheated bath at 135 ° for two hours. The solvent was removed at 40 ° (0.1 mm) to give an oil which was dissolved in 100 ml of ethyl acetate. The ethyl acetate solution was washed twice with 100 ml portions of water and extracted twice with 100 ml of saturated aqueous sodium bicarbonate solution (final pH 6.7). The aqueous layers were separated, combined and stirred with 100 ml of ethyl acetate. The aqueous solution was adjusted to pH 2 with 40 ° H 2 PO 2 and the organic extract was separated. The solution was extracted twice more with 100 ml portions of ethyl acetate and the extracts were azeotroped and distilled azeotropically to give an oil at 35 ° C (15 mm). The residue was slurried with Skellysolve B and collected as a tan-colored amorphous powder weighing 6.2 g. The solids were suspended in 80 ml of water and saturated sodium bicarbonate solution was added until all the material dissolved (final pH 7.5 ). A solution of 4 g (0.011 mol) of N, N'-dibenzylethylenediamonium diacetate (DBED) in 75 ml of water was added and the mixture was stirred for 0.5 h with 150 ml of methyl isobutyl ketone in a two-phase system. The mixture was stored at 25 ° C for 5 days. The crystalline DBED salt of 4 was collected and washed with water and finally with acetone. After air drying, the salt weighed 4 g: m.p. 150-15Z deck.

Analysis calculated for 3 H 2 O: C, 57.53; H, 5.90; N, 12.43. Found: C, 57.54; H, 6.21; N. 12.71.

D) 73- (D-α-Aminophenylacetamido) -3-methyl-3-cephem-4-carboxylic acid (Cephalexin) (6) via Hetacephalexin (5).

To a solution of 1 g (0.0025 mol) of the compound (4) in 50 ml of dioxane (purified through a column of alumina), a stream of dry hydrogen chloride was introduced for 5 minutes. at room temperature. The solution was evaporated at 30 ° (15 ml) to a rubber which was slurried with ethyl acetate and collected. The solid was then dissolved in water (50 ml) and basified with aqueous sodium bicarbonate solution to a pH of 4.8. The mixture was filtered and the filtrate was evaporated at 30 ° (15 mm) and further dried by azeotropic distillation with ethyl acetate. The yield of the sodium salt was 600 mg (63¾). The NMR and IR spectra were consistent with the spectra of the acetone condensation product with cephalexin (5).

A solution of 1 g (0.0024 mol) of sodium hetacephalexin (5) in 5 ml of water was adjusted to pH 3.5 with 6 N hydrochloric acid and stirred at room temperature for approx. 12 hours while a solution of nitrogen was bubbled through the solution to remove the acetone formed during the reaction. The white crystalline cephalexin was collected, the filtrate was adjusted to pH 3.5 again and brought to a volume of 5 ml and the procedure repeated. The initial portion weighed 350 mg after drying in vacuo over 1 ^ 5 * ^ one <^ one portion weighed 240 mg, yielding a total yield of 590 mg (70¾). The NMR and IR spectra were identical to the authentic cephalexin spectra.

Example 2.

A) 6- (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -penicillanic acid (N-nitrosohetacillin)

To a suspension of 7.1 g (0.02 mol) of hetacillin in 350 ml of water was added dropwise at room temperature 6 N hydrochloric acid until all the hetacillin had dissolved. The solution was cooled in an ice bath to 10 ° and layered with 100 ml of ethyl acetate. A total of 1.4 g (0.02 mole) of sodium nitrite dissolved in 25 ml of water was added in small portions over a period of 5 minutes. The solution was stirred for 20 minutes at 10 ° and the ethyl acetate layer was separated, washed with water and evaporated at 5 ° under reduced pressure (15 mm) to a yellow oil which crystallized after slurrying with ether. The product was recrystallized from methanol-water to give 4.5 g of crystals (54¾ yield); m.p. 195 DEG C. decomposition).

Analysis calculated for ^ 9 ^ 24 ^ 4 ^ 5 ^ C, 54.54; H, 5.50; N, 13.39.

Found: C, 54.55; H, 5.58; N, 13.33.

Ir (KBr) 2800 to 3600 cm "1 (carboxyl OH), 1803 and 1790 (8-lactam / O₂ CN), 1750 and 1730 (carboxyl C and imidazolidinone CN), 700 (Cg H DMSO dfi), 7.30 ppm 5 (S, 5, CgHg-), 5.64 (S, 1H-CH-N), 5.60 (d, 1, J = 4 cps, NCHCO), 5.45 (d, 1, J = 4 cps, NCHS), 435 (S, 1, NCHCO), 2.00 (S, 6, CH3CH3CN), 1.48 (S, 6, CH3CH3CS).

B) 6- (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -penicillanic acid sulfoxide (N-nitrosohetacillin sulfoxide).

A total amount of 10 g (0.024 mol) of 6- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid was dissolved in 100 ml of water at a pH of 8 at dropwise addition of 10¾ sodium hydroxide. After cooling to 0 °, a solution of 6 g (0.025 mol) of sodium metiodate in 100 water was added and stirring was continued for 3 hours. The pH of the solution was lowered to 2 with 1: 1 phosphoric acid. The product was extracted into ethyl acetate, washed with water, and the solution azeotroped to give an oil which, by slurrying with ether, crystallized to give 6.5 g of white crystals; melting point> 160 ° (slow decomposition). An analytical sample was recrystallized from dimethylformamide and water.

12 145629

Analysis calculated for: C, 52.52; H, 5.11; N, 12.92.

Found: C, 52.66; H, 5.37; N, 13.45.

Ir (KBr) 3540 cm -1 (hydrate OH), 2400 to 3400 (carboxy OH), 1804 0 op (B lactam CN), 1720 to 1750 (imidazolidinone CN and carboxyl C), 1050 (S-HO), 705 ( C6H5-); nmr (DMSO dg), 7.32 ppm δ (S 5, CgHg-), 5.77 (S, 1,> - CH-N), 5.72 (d, 1, J = 4.5 cps NCHCO), 4.83 (d, 1, J = 4.5 cps, NCHS), 4.30 (5, 1, NCHCO), 2.12 and 2.05 (S, S, 6 CH 2 CH 2 CN), 1.47 and 1.20 (S, S, 3, 3, CH 2 CH 2 Cl).

C) Conversion of 6- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide (N-nitrosohetacillin sulfoxide) to N-nitrosoheta-cephalexin.

To a stirred solution of 2 g (0.0048 mol) of N-nitrosohetacillin sulfoxide dissolved in 100 ml of tetrahydrofuran was added 0.5 g (0.0050 mol) of triethylamine. The triethylammonium salt precipitated and 320 mg (0.0023 mole) of dichlorodimethylsilane was added to the slurry, which cleared considerably after a few minutes. Stirring was continued for 45 minutes. The triethyl ammonium chloride was removed by filtration and the tetrahydrofuran was evaporated under reduced pressure to give an oily pale yellow residue which was dissolved in 100 ml of tetramethylurea and 3 g of acetic anhydride. The flask was rinsed with nitrogen and the solution was heated at 130 ° for 1 hour. The tetramethylurea was removed at 35 ° at 0.1 mm and the residue was dissolved in ethyl acetate and extracted with dilute sodium carbonate solution at pH 8.5. The basic solution was separated and the pH lowered to 2 with 1: 1 phosphoric acid and the precipitate extracted into ethyl acetate, washed with water and dried by azeotropic distillation to give N-nitrosohetacephalexin as a solid weighing 470 mg. A bioautograph of this solid (opposite a B.subtilis grafted agar plate) of a cellulose plate developed with n-butanol, ethanol, and water (4: 1: 5) showed a biologically active spot corresponding exactly in R -nitrosohetacephalexin. Both samples were resistant to penicillinase.

D) 7- (D-α-Aminophenylacetamido) -3-methyl-3-cephem-4-carboxylic acid by reduction of N-nitrosohetacephalexin with zinc and acetic acid.

To 500 mg of 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazo-lidinyl) -3-methyl-3-cephem-4-carboxylic acid dissolved in 20 ml of 90 ° acetic acid 500 mg of zinc dust was added. The mixture was stirred at 5 ° on an ice bath for 3 hours. The zinc was collected by filtration and the filtrate was evaporated at 0.1 mm to an oil which was slurried with ether and solidified to give 420 mg. The Ir spectrum showed a B-lactam at 1755cm ^, amide carbonyl at 1695cm ^ and a strong carboxylate at 1580cm ^. The bioautogram of this solid (opposite a B.subtilis grafted agar plate) of paper strip What, no. 1 in an n-butanol, ethanol, water (4: 1: 5) system showed a biologically active stain corresponding in R ^ value to authentic 7- (Da-amino-phenylacetamido) -3-methyl-3-cephem-4 -carboxylic acid (cephalexin). The 420 mg was further purified by dissolving in 7 ml of water at pH 8 by the addition of NaSH. The zinc sulfide was collected and the filtrate was evaporated to an oil which solidified to give 31 mg. The infrared spectrum was identical to that of authentic cephalexin.

Example 3 7- (D-α-Aminophenylacetamido) -3-methyl-3-cephem-4-carboxylic acid by thermal rearrangement of N-nitrosohetacillin sulfoxide followed by Zn-HOAC-spalι-πτησ.

To 2 g (0.0048 mol) of 6- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide dissolved in 150 ml of tetrahydrofuran was added 0.5 g (0.0050 mol) of triethylamine and 0.32 g (0.0025 mol) of dichloro-dimethylsilane. The mixture was stirred for 1 hour and filtered. The filtrate was evaporated under reduced pressure to oil which was dissolved in 100 ml of tetramethylurea and 10 ml of acetic anhydride. The solution was heated to 120-122 ° for 1 hour. The tetramethylurea was evaporated at 35 ° at 0.1 mm to a dark brown oil which was dissolved in ethyl acetate and extracted at a pH of 7-8 with dilute sodium carbonate solution. The aqueous solution was separated, washed with ether, acidified to pH 2 with 1: 1 phosphoric acid and extracted into ethyl acetate. The ethyl acetate was evaporated under reduced pressure and the oily residue of N-nitroso-hetacephalexin was dissolved in 30 ml of 90 ° acetic acid and stirred for 2 hours at 10 with 2 g of zinc dust. The zinc was collected by filtration and the filtrate was evaporated at 30 ° at 0.1 mm to an oil solidified by dry ether slurry to give 470 mg of cephalexin. Its paper chromatogram (What. No. 1) against a B-subtilis seeded agar plate developed with n-butanol, ethanol and water (4: 1: 5) showed the zone of inhibition exactly equal to the R for value of authentic 7- (Da-aminophenyl) (acetamido) -3-methyl-3-cephem-4-carboxylic acid (cephalexin).

Example 4

Hydrogenolysis of 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazoli-dinyl-3-methyl-3-cephem-4-carboxylic acid by Raney nickel for dan- cephalexin .___

A suspension of 1 g (0.0024 mol) of 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl-3-methyl-3-cephem-4-carboxylic acid and 1 g wet Raney Nickel No. 28 was shaken for 2 days under 50 psi hydrogen pressure.

14 145629

After 1 day, an additional 2 g of catalyst was added in 25 ml of water.

When 2.5 equivalents of hydrogen was taken up, the nickel was removed by filtration and the solution was adjusted to pH 2 with 2N hydrochloric acid. The mixture was filtered and the filtrate adjusted to pH 4.7 with 101 sodium hydroxide and evaporated at 35 ° at 0.1 mm to give cephalexin as a white solid weighing 0.6 g. A paper chromatogram of this solid (opposite a B. subtilis grafted agar plate (What no. 1)) developed with n-butanol, ethanol and water 4: 1: 5 showed an inhibition zone exactly equal to the R R value for authentic cephalexin.

Example 5 6- (2,2-Dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) penicilic acid (N-formylhetacillin)

To a solution of 25 g (0.06 mol) of hetacillin in 50 ml of 97¾ formic acid was added 15 ml of acetic anhydride. The solution was stirred for 15 minutes and the temperature increased to approx. 40 °. The solution was diluted with 100 ml of water and the white crystalline solid was collected and air dried overnight. The yield was 22 g, mp 210-215 ° dec.

Analysis calculated for ^20 2022 ^3.55 ° C, 57.53; H, 5.55; N, 10.06.

Found: C, 57.20; H, 5.85; N, 10.04.

B) 6- (D-2,2-Dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) -penicillanic acid sulfoxide (N-formylhetacillin sulfoxide).

To 12 g (0.024 mol) of N-formylhetacillin dissolved in 250 ml of water at pH 8 (10% NaOH solution) was added 6.2 g (0.03 mol) of sodium methiodate. The solution was stirred for 3 hours at room temperature and then acidified to pH 2 with 1: 1 phosphoric acid. The product was collected, washed with water and air-dried overnight to give 3.5 g of the sulfoxide, mp 210-215 ° dec. After recrystallization from dimethylformamide and water, the analytical sample was dried in vacuo over P 2 O 5 at 56 °.

Analysis calculated for ^ 20 ^ 23 ^ 3 ^ 6 ^ '1/2 1 ^ 0: C, 54.30; H, 5.25; N, 9.51. Found: C, 54.01; H, 5.44; N, 9.99.

C) Conversion of 6- (2,2-dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide to N-formylhetacephalexin.

To a solution of 2 g (0.0047 mol) of 6- (2,2-dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide in 100 ml of tetrahydrofuran was added 0.48 g (0.0048 mol) of triethylamine. . After stirring at room temperature for 15 minutes, 0.52 g (0.0048 mol) of trimethylsilyl chloride was added and a precipitate of triethylammonium chloride was observed after a few minutes. Stirring was continued for 15 minutes and the salt removed by filtration and discarded. The tetrahydrofuran was evaporated under reduced pressure (15 mm) leaving a gummy residue which was dissolved in 35 ml of tetramethylurea and 3 g of acetic anhydride. The solution was heated to 131 ° for 1 hour. The tetramethylurea was removed by distillation at 0.1 mm and 35 °, and the residue was dissolved in ethyl acetate and extracted at pH 8.5 with sodium carbonate solution. The aqueous layer was separated, washed with ethyl acetate and acidified to pH 2 with 1: 1 phosphoric acid. The mixture was then extracted twice with ethyl acetate, washed with water and evaporated at 35 ° and 10 mm. The residue was dissolved in 15 ml of methanol and treated with charcoal (Darko KB). The charcoal was removed by filtration and the methanol was diluted with water and stored overnight. A yellow solid was collected and weighed 120 mg. The sample was slurried with ethyl acetate to give 22 mg of N-formylhetacephalexin as a pale yellow solid. The ir spectrum was identical to that of authentic 7- (2,2-dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid prepared by another course of action. The bioautogram of this solid (opposite B. subtilis grafted agar plate) on a paper strip (What. No. 1 paper) in an n-butanol, ethanol, water system (4: 1: 5) showed a biolotically active spot corresponding to exactly in R £ value for the authentic sample.

D) Acid hydrolysis of 7- (2,2-dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid to cephalexin.

To a solution of 415 mg (0.001 mol) of 7- (2,2-dimethyl-3-formyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid dissolved in 25 To 60 ml of dioxane solution was added 1.4 ml of 1.5 N hydrochloric acid. The solution was heated in a steam bath for 15 minutes and stored at room temperature overnight. The solvent was removed by vacuum distillation at 35 ° and 0.1 mm and a white solid obtained weighing 275 mg. The bioautogram of this solid against a B.subtilis grafted agar plate on a paper strip (What. No. 1) showed two biologically active spots in a system of n-butanol, ethanol and water (4: 1: 5) corresponding in R values for the starting material and cephalexin.

Example 6

Pyrolysis of sodium N-nitrosohetacillin sulfoxide and cleavage with dry hydrogen chloride.

A solution of 2.2 g (0.00475 mol) of sodium 6- (2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanate sulfoxide in 100 ml of tetramethylurea at 5 ° was treated with 0.32 g (0.0025 mol ) dichloro-dimethylsilane. The mixture was stirred for 1 hour and 10 ml of acetic anhydride was added. The mixture was then heated to 120 ° for 1 hour and the tetra-methylurea was evaporated at 0.1 mm at 35 ° to obtain a dark brown residue. This was dissolved in 50 ml of ethyl acetate and extracted twice with sodium bicarbonate solution. The basic extracts were combined, washed with ethyl acetate and finally with ether. The aqueous solution was acidified with 1: 1 phosphoric acid and the product extracted into ethyl acetate. The ethyl acetate was evaporated at 35 ° and 15 mm to a brown rubber. The product was collected in the least amount of ethyl acetate and precipitated with "Skelly-solve B" to give 250 mg of N-nitrosohetacephalexin. The material was dissolved in 59 ml of dioxane and dry hydrogen chloride gas was passed through for 5 minutes. The solution was stirred for 5 minutes and the solvent removed under reduced pressure at 15 mm and 35 ° to give cephalexin as a solid which was slurried with ethyl acetate and then weighed 200 mg. The paper chromatogram (What. No. 1) against a B.subtilis grafted agar plate developed with n-butanol, ethanol and water (4: 1: 5) showed an inhibition zone corresponding exactly in R 2 to authentic cephalexin.

Example 7

Sodium 6- (2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanate sulfoxide.

To a solution of 7.6 g (0.092 mol) of anhydrous sodium acetate in 30 ml of water and 350 ml of n-butanol was added 35 g of 6- (2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) pennicillanic. The mixture was stirred and filtered. The solution was evaporated at 35 ° and 15 mm to 1/3 of its original volume. A total of 100 ml of anhydrous n-butanol was added and the salt was collected and air dried. It was then dried at 0.1 mm over P 2 O 5 to give 29.8 g.

O: C, 48.30; H, 4.92; N, 11.8.

Found: C, 48.61; H, 5.17; N, 11.07.

Example 8 7- (D-α-Aminophenylacetamido) -3-methyl-3-cephem-4-carboxylic acid by hydrogen chloride cleavage of N-nitrosohetacephalexin.

To a solution of 2 g (0.05 mol) of 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid dissolved In 50 ml of dioxane, dry hydrogen chloride gas is bubbled for 5 minutes. The solution was stirred for 5 minutes and the solvent removed at 30 ° and 15 mm.

The residue was stirred with ethyl acetate and collected to give 1.9 g of crude product. The material was dissolved in dilute hydrochloric acid at pH 2.5 and treated with charcoal (Darko KB) for 5 minutes and the filtrate adjusted to ..................

17 is conducted at a pH of 4 with 10¾ sodium hydroxide. The water was evaporated at 40 ° and 15 mm to give 1.1 g of the free amino acid. The infrared spectrum was consistent with the spectrum of authentic cephalexin. Residue NaCl 38.34¾. The biological strength was 350 µg / mg. The chemical strength was 365 µg / mg.

Example 9

Conversion to cephalexin of 6- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide using a mixed anhydride method.

The procedure of Example 6 with the silylester was applied to 6.5 g (0.014 mole) of N-nitrosohetacillin sulfoxide sodium salt, 6 ml of acetic anhydride and 1.18 g (1.3 ml) of acetyl chloride. 2.4 g (41.5¾) of product were isolated. After treatment with dry hydrogen chloride in the usual manner, a total of 900 mg of cephalexin was isolated. A paper chromatogram (What. No. 1) against a B-subtilis grafted agar plate developed with n-butanol, ethanol and water (4: 1: 5) showed an inhibition zone corresponding exactly in R 2 value to authentic cephalexin.

0 145629. 18

Example 10

Φ Oh

\ / O

f-f I .ch3 ON-N l_r-r'8 '/ TSA ίΗ i \

/ K CH3 TMU

CH2 CH2 0 C02H ^ 13Jo C19H22 ^ 4 ^ 6 ^ t434-47) φ .0 Λ '/

CH-C

i - I ^ ON-N N-1—

CH3'X> ScH3 O

co2n C19H20N4 ° 5S C416 · 4 ^ HCl v ^ dioxane

ISLAND

d) Π II c

\ h- / V5 - “- c-nh ^ sN

v-rO 5 ^ nh * ΎΥκ

0¾ CH3 0 ^ "Y®3 CO3H

CO 2 H C 19 H 21 N 3 ° 4S t 387 · 45 3 C 16 H 17 N 3 ° 4S (347 · 39) 7- (D-2,2-Dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3- cephem-4-carboxylic acid .___________

A solution of 21 g (0.0487 mol) of 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) penicillanic acid sulfoxide and 5 g of p-toluenesulfonic acid (anhydrous) (TSA) ) in 500 ml of tetramethylurea (TMU) was heated to 135 ° for 2 hours with stirring. The solvent was removed at 0.1 mm at 40 °, leaving an oil which was dissolved in 250 ml of ethyl acetate. The ethyl acetate was washed twice with 100 ml portions of water and extracted with dilute sodium bicarbonate solution. The final pH was 6.7. The aqueous layer was separated and stirred with 100 ml of ethyl acetate. The pH was adjusted to 2 with 1: 1 H 2 PO 2 and the aqueous solution was extracted twice with ethyl acetate. The ethyl acetate was washed with water and azeotroped to an oil at 35 ° (15 mm). The residue was slurried with "Skellysolve B" and collected as an amorphous powder weighing 10.0 g. The solids were suspended in 150 ml of water and saturated sodium carbonate solution was added until all the material dissolved (final pH 7.5). A solution of 4 g (0.011 mol) of dibenzylethylene diamine diacetate in 75 ml of water was added and the mixture was stirred with 150 ml of 4-methyl-2-pentanone in a two-phase system. The mixture was stirred for 1 hour at room temperature and the crystalline salt was collected, washed with water and finally with acetone, and after air drying weighed 7.1 g; mp 150-152 ° dec.

Calcd. For .delta. C, 57.53; H, 5.90; N, 12.43.

Found: C, 57.54; H, 6.21; N, 12.71.

57.49 6.38

Ir (KBr) 3200-3600 cm -1 (NRH2 +); OH (water); 1760-1770 0 0

II II

(Β-lactam-C-N); 1600 ¢ 0-0-); 755, 700 C6H5.

The 7.1 g of Ν, Ν-dibenzylethylenediamonium 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem carboxylate was suspended in 50 g. 1 ml of phosphoric acid and 150 ml of water. The mixture was layered with 150 ml of ethyl acetate and shaken vigorously until all the salt dissolved. The ethyl acetate was removed, washed with water and evaporated at 40 ° (15 mm) to a crystalline solid weighing 3.1 g; mp 175-180 ° dec. The ir and nmr spectra were identical to the spectra of authentic N-nitrosohetacephalexin.

7- (D-2,2-Dimethyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid (fhetacephalexin)

To Ig (0.0025 mol) 7- (D-2,2-dimethyl-3-nitroso-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-cephem-4-carboxylic acid in 50 ml dioxane (purified by running through a column of alumina) was added dry hydrogen chloride for 5 minutes at room temperature. The solution was evaporated at 30 ° (15 mm) to a rubber which was slurried with ethyl acetate and collected. The solid was then dissolved in water (50 ml) and basified with aqueous

Claims (2)

Sodium bicarbonate solution to pH 4.8. The mixture was filtered, although the filtrate was evaporated at 30 ° (15 mm) to a glass-like substance which was further dried by azeotropic distillation with ethyl acetate. The yield of the sodium salt was 600 mg; the product was determined to be the sodium salt of 7- (D-2,2-dimethyl-5-oxo-4-phenyl-1-imidazolidinyl) -3-methyl-3-ce-phem-4-carboxylic acid (hetacephalexin), m.p. 205 ° C, decomposition. Analysis calculated for C C ^H₂NN₂O ^SNai O: C: 53.39, H: 5.19, N: 9.83. Found: C: 53.63, H: 5.00, N: 9.76. IR (KBr), 3600-2600 cm -1 (H2 O, NH, CH2, CH3 and CH'S), 1760 cm60 1 (Φ-lactam carbonyl), 1690 cm ”1 (amide carbonyl), 1590 cm” '(carboxylate) -carbonyl and C = C), 710 cm -1 monosubstituted phenyl. NMR (100 MHz) 20 mg. Sample in 0.4 ml of D 2 O with 2 drops of 0.1 NHCl 1; chemical shifts in ppm. from TSP; 7.52 (S, 5H's monosubstituted phenyl), 5.71 (IS, 1H, CH-N '), 5.28 (AB, 2H's f -CH2-C =), 2.26 (S, 3H »S = C-CH3), 1.88 and 1.80 (two S's, 6H's C (CH3)). This compound was found to inhibit D. pneumoniae (+51 serum) at a concentration of 0.3 mcg / ml, Str. pyogenes (+ 5¾ serum) at 0.3 mcg / ml, S. aureus Smith at 0.6 mcg / ml, Sal. enteritidis at 4 mcg / ml and Pr. mirabilis at 8 mcg / ml. A process for the preparation of cephalexin of the formula a o CH - C - NH-i -— f 1¾ oJ-ch3. in COOII or hetacephalexin of the formula - C - »-XS \ == J NH / -N CH3 COOH / C \ CH3 CH3. II or a non-toxic, pharmaceutically acceptable salt thereof, characterized by the following consecutive steps A) blocking the -3-imino group in hetacillin of the formula 21 N-f Ύ-° η3 N -CtT 'j ^ CHo JN-1- COOH CH 3 do III by nitrosation or formylation to give an intermediate of the formula -k M CH, OH-C ΠΗ. In OK, X --- 11 -L- OOH OH, 30 · wherein Z represents nitroso or formyl, B) oxidizing the aforementioned intermediate or a salt thereof to produce a sulfoxide intermediate of formula Γ \ _ * ° s / ¾ —r ¥ h3> - 'zN- G ^ I' CH0 -_N-L_ COOH CH ^ 0 ^. V or a salt thereof, and, if desired, blocking the carboxylic acid group of the above-mentioned sulfoxide in a manner known per se to produce a sulfoxide intermediate of the formula 22 145629 π Λ O .0 // I! ^ CHo · V / - C ^ 'S. / J \ _. / Ί N -—-- S V-CHo X- 'ZN -Cd 1 ^ 0¾ i_N_-L C00B CII3 ox We wherein C00B represents a protected carboxyl group and Z has the meaning given above, C) heating of the above-mentioned sulfoxide intermediate V or VI in an inert organic solvent in the presence of an acid catalyst to produce a cephalosporin intermediate of the formula ao H CH - cx q I N --- f N & -N-cr "I CII3 / y - N. CII3 and X VII wherein Z has the meaning given above and X represents COOH or COOB or a salt thereof and, if necessary, removal of the carboxyl protecting group in a manner known per se, and D ) cleavage of the imino-blocking group to produce hetacephalexin of the formula lin / N \ / o compound for producing cephalexin of the formula