Process for the preparation of the syn-isomer or of a mixture of syn- and anti-isomers of novel antibiotically active 7 beta -acylamino-ceph-3-em-4-carboxylic acids

摘要

Novel, antibiotically active compounds of the formula I IMAGE in which the symbols B, R, Ra, Rb, m, n and Z have the meaning given in Patent Claim 1, are prepared in the form of the syn-isomer or of a mixture of syn- and anti-isomers, the content of the syn-isomer being at least 90%, by N-acylating an appropriate 7 beta -amino compound or an acid derivative of this compound by reaction with an acylating agent donating the appropriate acyl group and in the form of the syn-isomer or of a mixture of syn- and anti-isomers, carboxyl protective groups present being removed and, if a ceph-2-em compound has been used as a starting compound, the ceph-2-em compound obtained is isomerised to the corresponding ceph-3-em compound. Compounds of the formula I obtained, in which B denotes &rdurule& S-O, can then be reduced to the corresponding, preferred compounds, in which B denotes &rdurule& S. The novel compounds are distinguished by an antibiotic activity having a broad spectrum of action, in particular by a high activity against Gram-negative microorganisms, including those which form beta -lactamases, and also have a high stability against beta -lactamases which are produced by some Gram-negative organisms.