CEPHALOSPORIN DERIVATIVES

Cephalosporin derivatives of the general formula wherein R1 is an acyl group derived from a carboxylic acid; R2 is hydrogen, hydroxy, lower alkyl-Q m, cycloalkyl, lower alkoxy, lower alkenyl, cycloalkenyl, lower alkynyl, aralkyl-Q m, aryl-Q m, aryloxy, aralkoxy or a heterocyclic ring, the lower alkyl, cycloalkyl, lower alkoxy, lower alkenyl, cycloalkenyl, lower alkynyl, aralkyl, aryl, aryloxy, aralkoxy and the heterocyclic ring being unsubstituted or substituted with at least one group selected from carboxy, amino, nitro, cyano, lower alkyl, lower alkoxy, hydroxy, halogen, -CONR4R5, -N(R5)COOR9, R5CO-, R5OCO- or R5COO- where R4 is hydrogen, lower alkyl, or cycloalkyl; R5 is hydrogen or lower alkyl; R9 is hydrogen, lower alkyl, lower alkenyl or a carboxylic acid protecting group; Q is -CO- or -SO2-; m is 0 or 1; n is 0, 1 or 2; as well as readily hydrolyzable esters thereof, pharmaceutically acceptable salts of said compounds and hydrates of the compounds of formula I and of their esters and salts. The products are antibacterially active.