Cephem compounds and processes for preparation thereof

Abstract From the Canadian patent

New 7-substituted-3-cephem-4-carboxylic acid derivatives are provided of the formula: wherein R1 is amino or protected amino A is lower alkylene, which may be substituted with oxo hydroxy, amino, protected, hydroxy or protected amino R2 is hydrogen, halogen or hydroxy, and R3 is carboxy or functionally modified carboxy their, nontoxic, pharmaceutically acceptable salts and bioprecursors thereof; the derivatives have antimicrobial activity against Gram negative and Gram positive bacteria.