Process for the preparation of a therapeutically useful pure, more polar diastereomer of (6R, 7R) -7- 2- (2-aminothiazol-4-yl) -2 (Z) - (methoxyimino) acetamido -3- (methoxymethyl) -3-kefem-4-carboxylic acid-1- (isopropoxycarbonyloxy) ethyl ester

摘要

Enterally absorbable diastereomers of (6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(Z)-(methoxyimino)acetamido]-3-(m ethoxymethyl)-3-cephem-4-carboxylic acid 1-(isopropoxycarbonyloxy)ethyl ester of the formula I IMAGE and its physiologically acceptable salts and also diastereomerically pure salts of the compounds of the general formula II IMAGE where HX represents a mono- or polybasic acid and where X represents an inorganic or organic physiologically acceptable anion, and a process for the preparation of these compounds of the formula I or II are described, which is characterised in that on mixing together one equivalent of a solution of the diastereomer mixture of the formula III with 0.2 - 2 equivalents of a solution of the acid component HY the more poorly soluble diastereomer of the general formula IV is first precipitated and separated off by filtration, then the more readily soluble diastereomer of the general formula IV is precipitated from the filtration solution, it being possible in the subsequent subsidiary steps for the acid components HY to be identical or different and any desired sequence of the addition of different acid components HY to be used, and the salts obtained are optionally further purified by crystallisation.