SE407064B - IN 7-FRAME PROTECTED 3-BROMOMETHYL-DELTAŸ2-CEPHALOSPORANIC ACID RESIDUES FOR USE AS AN INTERMEDIATE IN THE PRESENTATION OF ANTIBIOTIC ACTIVE DELTAŸ3-CEPHALOSPORANIC ACID DERIVATIVES - Google Patents

Description

M1 10 15 20 25 BO _35 HO N 7200411 -2 i 7 få \ R- - -HN-CH- C1i6 2 CO-H5 3] CH (I) s cháç- 3 I l C001! in which R is the residue of the acylamido group in the 7-position, and R1 is hydrogen, a salt-forming cation, an ester group or an anionic charge when C00- forms a salt with a cation, either inside or outside the molecule.

In attempts to improve and develop the properties and utilization of these semi-synthetic cephalosporin-derived penicillin compounds, efforts have been made to change the 3-methyl group of the above-mentioned 3-desacetoxycephalosporins to a group which gives the resultant the cephalosporin compound increased antibiotic activity against one or more gram-positive or gram-negative microorganisms. However, so far it has not been possible to directly convert an ESES3-desacetoxycephalosporin to a 3-methyl-functionalized ÉÉÄ3-cephalosporin in any particular exchange. Consequently, in the field of chemical antibiotics, there is a need for an alternative method or route for obtaining the inherently stronger fi§3-3-methyl-functionalized cephalosporin antibiotics, which have hitherto only been obtained from fermentation-derived cephalosporin Ci and the one obtained therefrom. 7-aminocephalosporanic acid (7-ACA). It is an object of the present invention to circumvent the difficulty of converting β-desacetoxycephalosporins to 3-methylfunctionalized β: β-cephalosporanic acid antibiotics. 2-7-Acylamido-3- (nucleophilic methyl) -cephalosporin esters can be partially converted to the corresponding propyl-7-acylamido-3-nucleophil-methyl-sulfide esters by heating them in a weakly basic medium, resulting in: The β-double bond shifts to the CC:> 3 position, giving rise to an equilibrium mixture of the product and the: 3-7-acylamido-3- (nucleophilic methyl) -cephalosporin ester, which is readily converted to an active antibiotic by removal of the ester group by known methods, as illustrated below. However, the 7-aylamido-3- (nucleophilic methyl) -3-cephem-1-carboxylate ester product can also be chemically 3-ester by one process, converted to the corresponding one which involves (1) oxidation of the 2-sulfide ester product to the corresponding § 3 sulfoxide ester with a peracid, (2) reduction of β 33-12011 - kn iO 25 a 7200411-2 such as sodium bisulfite or a sulfoxide ester with a reducing agent sodium dithionite in the presence of an activator such as acetyl chloride in organic diluent such as acetic acid or dimethylformamide to give sulfide , and (3) subsequent deesterification of the 3-sulfide ester, if desired, to the antibiotically active 4:> 3-sulfide acid. If desired, mixtures of the active 3-ophalosporic acid antibiotic and the inactive 2-cialicosporic acid, and pharmaceutically acceptable salts thereof, may be used in this mixed form for certain antibiotic purposes, for example as a topical antibiotic for open wounds for veterinary medicine. use, in which case the mixture can be powdered on the wound, or mixed into an ointment and applied in this medium to inhibit the growth of various gram-positive or gram-negative microorganisms. The 2-desacetoxycephalosporin ester starting materials can be obtained from a variety of penicillin or cephalosporin sources by known methods. They are obtained by treatment with the base of the corresponding 3-methylquene-3-cephem-H-carbexylate ester as described, for example, in Example Ä of U.S. Pat. No. 3,276,626. They can also be obtained by hydrating a cephalosporin ester derived from cephalosporin C to give the corresponding fl j-desacetoxicephalosporin ester, and subsequently treating the aqcšgj-desacetoxieeïalosporin ester with a base, such as pyridine 1000 to cool ( the double blend to the> 52 double blend stand. Attempts to brominate the allylic 3-methyl group in the low-desacetovicephalosporanate esters were unsuccessful. The successful bromination of the β-β-desacetoxy-cephalosporanate esters according to the invention was surprising and unpredictable. The amino protecting group represented by R in the above formula may be any known group capable of protecting the nitrogen to which it is attached from N-bromosuccinimide attack. If the nitrogen is in the free amino state, excess brominating reactant must be present to accomplish the purpose of the first step of the process of the invention. The group R may be, for example, triphenylmethyl (trityl), trimethylsilyl or, which is most practical and most suitable, an acyl group. Many acyl groups suitable for this purpose are already known in the penicillin and cephalosporin antibiotic literature. Some of these acyl groups may be exposed to bromerine n, in which full N-chromosuccinimide 2 excess would be needed to hydrate the entire 3-methyl group Håål - M1 in the lvzooan-z% -desacetoxycephalosporanate ester. For example, if thienylacetyl or furylacetyl is used as the acyl protecting group, the ring systems of these groups may be brominated in the first step of the present process but this condition is not detrimental to the preparation of antibiotics from the intermediates, especially as the 7-aeyl group will be cleaved later in the process. corresponding to the 7-aminocephalosporin ester derivative. However, the preferred amino protecting group is an ayl group of the formula 10 - (cn 2) n ___ co in which n is 1 and X is oxygen or a chemical bond.

The designation RJ represents the residue of an ester-forming alcohol. The alcohol used to obtain these esters should be an alcohol which can be removed by known methods, such as by using a dilute aqueous base or by using trifluoroacetic acid, or by hydrogenation in the presence of a palladium or rhodium catalyst on a suitable support such as carbon, barium sulphate or alumina so that the cephalosporin is not degraded. The preferred ester groups are those listed above.

According to the present invention, the esterified β-2-desacetoxycephalosporin starting material is mixed with N-bromosuccinimide in an organic, liquid medium and stirred until the β-bromomethyl product is formed. The reaction is preferably carried out in the presence of azoblsisobutyronitrile as catalyst or initiator to improve the yield, but the process can be carried out without catalyst. The reaction proceeds more rapidly when the mixture is heated slightly and for this reason a temperature range of from about 4000 to about 10000 is used. should be kept below the decomposition point of the starting material and the product. In addition, too low temperatures cause the reaction to proceed too slowly to be effective; the N-brumosucoimide is usually present in at least stoichiometric amounts with respect to the fi š2-desacetoxicephalosporanate tower as the latter is the most expensive. The amount of azohisisobutyronitrile or the amount of other initiator used is not critical. Organic liquid diluents for the reaction mixture include carbon tetrachloride or mixtures thereof with chloroform, tetrachloroethane, methylene chloride, benzene, toluene, xylene, heptane and the like.

Examples of the novel β-bromomethyl intermediate compounds of the present invention include the following compounds: M-methoxybenzyl-7-phenylacetamido-3-bromomethyl-α 2-cephem-M-carboxylate, 4-methylbenzyl-7-phenylacetamido-3-bromomethyl-β: β-cephem-β-carboxylate, benzhydryl-7-phenylmercaptoacetamido-3-bromomethyl-β-cephem -H- -carboxylate, 'teptbutyl-7- (H'-nitrophenoxyacetumidu) -3-bromomethyl-β-carbon-α-carboxylate, 3,5-dimethoxybenzyl-7- (3'-chlorophenylmercaptoacetamido) -3 -bromo-methyl-α-β-cephem-β-carboxylate, tert-butyl-7- (α'-iodophenoxyacetamido) -3-bromomethyl-α-β-cephem-4-carboxylate, 3-mG , 5'-dibromophenoxyacetamido) -3-5-bronomethyl-α-ACE-2-cephem-α-carboxylate, phthalimidomethyl-7-benzamido-3-bromomethyl->> 2-cephem-α-carboxylate, succinimidomethyl-7- (4 ' -trifluoromethylphenoxyacetamido) -3-bromo-methyl-β >> 2-cephem-H-carboxylate, and 'tert-butyl-7- (h'-fluorophenyl-mercaptopropionamido) -3-bromomethyl-1-β-cephem-M-carboxylate, tert-butyl- 7-phenoxLu cetamido-3-bromomethyl-C 1-6-cephem-1-carboxylate, p-nitrobenzyl-7-phenylacetamido-3-bromomethyl-2-cephem-1-carboxylate, 1,1-dimethyl-2-propenyl-7-phenoxyacetamidoph3 -bromomethyl-β-cephem-# -carboxylate, 1,1-dimethyl-2-propynyl-7-phenoxyacetamido-3-bromomethyl-α2 -2-cephem-H-carboxylate. The invention is further illustrated by the following detailed examples which illustrate the preparation of the α-desacetoxylcephalosporin esters of the present invention. Preparation of g-acid 3.63 g (0,01 mol) of methyl 7- (phenoxyacetamido) -3-methyl-β; 3-cephem-β-carboxylate (prepared from desacetoxicef-V and diazo methane), in 100 ml of pyridine and water in a ratio of 1zl was cooled in a bath of ice and water, an equivalent of 1N NaOH was added, and the mixture was stirred in the cold for 5 hours. After dilution with 100 ml of water and 100 ml of cbyl acetate was cooled the mixture and acidified to pH = 2.5 with 20% HCl. The ethyl acetate was removed and the aqueous layer was extracted once with ethyl acetate. The combined organic and organic layers were extracted once with ethyl acetate. The layers were cooled, water was added and the pH was adjusted to 8.2 with solid NaUCO 3, the aqueous layer was removed, washed once with ethyl acetate, then cooled and layered with ethyl acetate and purified to pH = 2.5.The ethyl acetate was removed, and the the aqueous layer was washed with ethyl acetate and the combined organic layers were washed two times. times with sodium chloride solution, dried over magnesium sulphate, filtered and evaporated to give a foam.

The foam product was dissolved in and crystallized from ethyl acetate to give 1,65 (H5%) 7- (phenoxyacetamido) -3-methyl-1H-2-cephem-1H-carboxylic acid, m.p. 180-13300 (dec.). 9 “-desacetoxicephalospornnsvru esterification a. , _ _. ,,. C: 2,. . β-Methoxybenzyl-3-methyl-7-phenoxyacetamido-gcyl-4-carnoxylate To a stirred suspension of 1,75 g (0.005 mol) of O-A2-desacetoxyceph-V-1-phenoxyacetamido-3-methyl-cephem-β -carboxylic acid] and 700 mg (0.005 mol) of p-methoxybenzyl alcohol in 20 ml of methylene chloride were added to a solution of a condensing agent containing 1.23 g (5% excess) of DNF-dneopentyl acetal in methylene chloride. The resolution was complete within minutes. The reaction mixture was stirred overnight at room temperature. The solvent was removed and benzene was added. After heating to effect dissolution, the mixture was allowed to stand at room temperature. After removal of a crystalline side reaction product, the benzene mother liquors were diluted, washed 3 times with bicarbonate solution, twice with sodium chloride solution, dried over magnesium sulfate and filtered. The residue was crystallized from CClH to give 4-methoxybenzyl-7-phenoxyacetamido-3-methyl-cephem-H-carboxylate.

The first fraction weighed 1.15 g, mp 108-112 ° C; the second fraction weighed 0.1 g, mp 107-111 ° C; 55% ubn§tc.

Functionalization of n-methoxybenzyl-3-methyl-7-phenoxyacetamino-2-cephem-H-carboxylate A mixture of 235 mg of p-methoxybenzyl-3-methyl-7-phenoxlacetamido-2-3-cephem-H-carboxylate, 90 mg N-bromosuccinimide (NDS), lay mg azobisisobutyronitrile and 30 ml CCl 3 were refluxed under nitrogen and protected from light under heat. The reaction mixture was cooled, filtered and the golden yellow filtrate evaporated to dryness. The structure of the 3-bromomethyl product was confirmed by NMR.

EXAMPLE 2 Preparation of 2- and β-methyl-3-acotoxymethyl-7-phonoxyacetimido-72-cephem-H-carboxylate mixture LO 15 20 N UI BO 35 40 v _ 720Ûh11-2 In a 50 ml round bottom flask 91 mg (0.25 mol) of crystalline methyl 3-methyl-7-phenoxyacetamido fi ššäz-cefom-α-carboxylate, 55 mg (0.25 mmol) of N-bromosuccinimide, 7 mg of azobisisobutyronitrile and 1.5 ml of K CCl obtaining motyl 3-bromomethyl-7-phenoxyacetamido-2-cephem-M-carboxylate. The mixture, protected from light, was refluxed under quenching gas under low temperature, cooled, filtered, and evaporated to dryness.

EXAMPLE 3 Esterification V To a stirred suspension of 6.98 g (0.002 ml) of 2,2-desacetoxy-cef-V-acid.§§-methyl-7- (phenoxyacetamido) 1¿: §2-cefem-ü carboxylic acid and 2.8 g (0.002 mol) of 4-methoxybenzyl alcohol in 100 ml of methylene chloride were added to a solution of β, 62 g of dimethylformanedineopentyl acetal in 25 ml of methylene chloride. The resolution was completed within a few minutes. The reaction mixture was stirred for M8 hours at room temperature to ensure complete reaction. The solvent was removed and benzene was added. The resulting solution was washed 3 times with aqueous sodium bicarbonate solution, 2 times with aqueous sodium chloride solution, dried over magnesium sulfate, filtered and evaporated. The residue was crystallized from carbon tetrachloride to give 6.7 g (92% yield based on unrecycled acetic acid) M-methoxybenzyl-3-methyl-7-phenoxyacetamido-β-cephem-α-carboxylate ester, m.p. 112 ° C. The spent aqueous sodium bicarbonate solutions were layered with ethyl acetate, cooled and their pH was adjusted to 2.5.

The organic layer gave 1.56 g of colorless, crystalline 3-methyl-7-phenoxyacetamido-2-cephem-H-carboxylic acid, which could be used again in the change process.

Functionalization of 3-methyl group 1.17 g of H-methoxybenzyl-3-methyl-7-phenoxyacetamido [2] cephem-4-carboxylate ester were treated with N-bromosuccinimide in carbon tetrachloride in the presence of azobisisobutyronitrile to give -3-Bromomethyl-7-phenoxyacetamido ester-cephem-α-carboxylate ester. Structure: confirmed by NMR.

EXAMPLE Ü Preparation of t-butyl-7- (phenoxyacetamido) -3-bromomethyl-α 2-cephem-4-carboxylate E: Analysis of 8.08 g (20 mmol) of Mt-butyl-7- (phenoxyacetamido) -3-Methyl 2-cephem-carboxylate, 5.0 g of N-bromosuccinimide and 50 mg of azobis-isobutyronifril in 800 ml of carbon tetrachloride were refluxed under nitrogen until a negative starch iodide sample was obtained (5 hours). The reaction mixture was cooled, the succinimide was removed by filtration and the solvent was removed under reduced pressure to give 1L, S g crude product.

. An NMR spectrum showed only the tert-butyl 7-phenoxyacetamido-3-bromo-methyl-β-§2-cephem-β-carboxylate, which was contaminated with traces of succinamide: yield 90%). EXAMPLE 5 Phenoxyacotamido-3-yl-α-2-bromomate Preparation of nitrohene's 1-7-defem-H-carboxylate A mixture of δ, 835 g β-nitrobenzyl-7-phenoxyacetamido-3-methyl-α-β2-cephem carboxylate, 80 ml of chloroform and 320 ml of carbon tetrachloride were heated to complete dissolution. To this solution was added 2.67 g of powdered N-bromosuccinimide and S2 mg of azobisisobutyronitrile, and this mixture was kept in an oil bath at a temperature of 8500 for 2 hours or 15 minutes. The reaction mixture was cooled to room temperature and the solvents were evaporated. A sample thereof was examined by NMR and the structure of the 3-bromomethyl product was confirmed. EXAMPLE 6 Verification of the structure of p-methoxybenzyl 7-phenoxyaceaamide-3-bromomethylsole of 2-cephem-4-carboxylate.

The crude N-bromosuccinimide productone (p-methoxybenzyl 7-phenoxyacetamide-dibasbromomethyl-cephem-H-carboxylate), prepared as described in Example 1, was examined by NMR spectroscopy. The presence of the alluvial bromide group was verified by peaks at 6.8 Gr. (crude doublet) depending on the vinyl hydrogen at carbon atom No. 2 in the allylic bromide (p-methoxybenzyl-3-bromomethyl 2-cephem-H-carhoxylate) and at ü, lÜ-year (quartet, J = 8 Hz) depending on the methylene group, which carries bromine. These absorbances indicate the presence of the allylic bromide in the crude reaction blue.

EXAMPLE 7 Confirmation of the structure of β-tert-butyl-7-phenoxyacetamido-3-bromomethyl-ÅQÄ? -Cephem-H-carboxylate-Û-bromosuccinimide product (tert.buty1-7-fi-enoxyacetamido-3-bromomethyl-2-cefomethyl -H-carboxylate), prepared as described in Example A, was confirmed by NMR spectroscopy. The following spectrum was obtained: NMR peaks:

Claims (2)

9 L 7200411-2 1.56 6 (S) tert.butyl 4.23 a (Q) -c fl zßr _ o 4.57 s (s) Phocnzt- 5.20 s (s) c-4 5.33 s ( D) _c-s 5.13 s (Q) _ cv 6.52 s (s) c-2 vinyl 6.87-6.89 6 (multiple aromatic group and NH At 1.95 there was only a small peak, which was only slightly above the noise level, which showed a negligible amount of starting material. 1. 7-position protected 3-bromomethyl-A2-cephalosporanic acid ester for use as an intermediate in the preparation of antibiotically active A3-cephalosporanic acid derivatives, characterized in that it has the formula / s NC * CH2Br n \ C, / o I 1 COOR in which R is phenoxyacetyl and RL is hydrogen, methyl, C4-C6-tert-alkyl, nitrobenzyl, or methoxybenzyl, or salts thereof. Ester according to claim 1, characterized in that R1 is methoxybenzyl. STATED PUBLICATIONS: Sweden 360 081 (CÜ7d 99/24) _Other publications: Karrer, P, Textbook of Organic Chemistry. 13 neubearb. & erw. Auft. Stuttgart 1959, pp. 95-96.