| abstract |
(A) Compounds salts and esters. R = carboxylic acyl; P = Cl, Br, I, formyloxy, isothiocyanato, or haloacetoxy. Preferred compounds have R = - (B) Compounds B = alkyls or B and the attached N atom represent an opt. subst. thiazole ring. - (C) Compounds - A together with the attached N atom = opt. subst. pyrazole ring. - Broad spectrum antibiotics. - Reaction of ceph-3-em-4-carboxylic acids or derivs. having an RNH group in 7-position and the group -CH2X in 3-position where the acid HX has a pKa or not greater than 4.0 and X does not contain an SH group, with a compound having a nucleophilic group in suitable conditions to displace X. |