1-CARBA-(DETHIA)-CEPHALOSPORIN DERIVATIVES

Compounds of formula I wherein R1 is hydrogen, lower alkyl which is unsubstituted or substituted by fluoro, aralkyl, cycloalkyl, -COR4 or -C(R5R6)CO2R7 -C(R5R6)CONHR7; where R5 and R6 are each independently hydrogen or lower alkyl, or R5 and R6 taken together form a cycloalkyl group; R4 is hydrogen or lower alkyl and R7 is hydrogen, lower alkyl, lower alkenyl or a carboxylic acid protecting group; R2 is hydrogen, hydroxy, lower alkyl-Qm, cycloalkyl, lower alkoxy, lower alkenyl, cycloalkenyl, lower alkynyl, aralkyl-Qm, aryl-Qm, aryloxy, aralkoxy, a heterocyclic ring or heterocyclyl lower alkyl, 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 which is unsubstituted or substituted by fluoro, lower alkoxy, hydroxy, halogen, -COR6, -C(R5R6)CO2R7, -C(R5R6)CONR5R8, -CONR5R6, -N(R6)COOR10, R6OCO- or R6COO- where R5 and R6 are hydrogen or lower alkyl; R7 is hydrogen, lower alkyl, lower alkenyl or a carboxylic acid protecting group; R8 is hydrogen, lower alkyl or phenyl which is unsubstituted or substituted with at least one halogen, hydroxy, amino, lower alkyl, or lower alkoxy; R10 is lower alkyl, lower alkenyl or a carboxylic acid protecting group; Q is -CHR-, -CO- or -SO2-; R is hydrogen or lower alkyl; R3 is hydroxy, -O-, lower alkoxy, -OM and M represents an alkali metal; m is 0 or 1; n is 0, 1 or 2; x is CH or N as well as readily hydrolysable esters thereof, pharmaceutically acceptable salts of said compounds and hydrates of the compounds of formula I and of their esters and salts are provided. These compounds have valuable antiinfective properties.