DK269679A - PROCEDURE FOR MADEING CEPHEM RELATIONS - Google Patents

Abstract

Cephem compounds of the general formula <IMAGE> in which A denotes hydrogen, an equivalent of an alkali metal or alkaline earth metal or an organic nitrogen base, or the radical of an ester group, R1 denotes hydrogen, and optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, acyl, aryl, arylsulphonyl, alkylsulphonyl or heterocyclic group, R2 denotes a furyl, thiazolyl or phenyl group which is optionally substituted by alkyl, aryl or an optionally protected amino group, and B denotes alkoxy, methyl, acetoxymethyl, carbamoylmethyl, halogen or CH2S-Het, where Het can denote a 5- to 6-membered ring having 1-4 carbon atoms, and in which R1O groups are located in the syn position and n denotes 0, 1 or 2, are prepared by reacting a carboxylic acid of the general formula <IMAGE> or a salt thereof, in the presence of approx. 0.1 to approx. 3.0 mol of a compound of the general formula <IMAGE> in which R3, R4 and R5 can be identical or different, and denote alkyl, with R3 and R4 or R3 and R5 also together being able to form a ring which is optionally interrupted by a heteroatom, and R5 also being able to denote a dialkylamino group in which the alkyl groups in each case contain 1-6 carbon atoms and can, where appropriate, be closed to form a ring which is interrupted by a heteroatom, with an acid halide former and reacting the resulting complex with a cephemic acid of the general formula <IMAGE> in the form of an amine salt or an ester which is optionally eliminable by acid hydrolysis or hydrogenolysis, or a silyl ester, and, if necessary, converting, in a manner known per se, any resulting carboxyl group into another of the groups specified under A. This process prevents isomerization, and homogeneous products in the syn form are obtained.