Novel c-3 s/o-and s/n formaldehe acetal derivatives of cephalosporins and their use as antibotics

The compounds of the general formula (I) wherein R 1 denotes a pharmaceutically acceptable side chain radical as used conventionally in the field of cephalosporins and wherein R 2 denotes a pharmaceutically acceptable group which is bonded to the remaining part of the molecule by an oxygen-carbon single bond or a nitrogen-carbon single bond, and their pharmaceutically acceptable salts, esters and amide derivatives are effective antibiotics. 1