3-pyrrolidylideeni-2-oni-kefalosporiinien johdannaiset

PCT No. PCT/EP96/00667 Sec. 371 Date Jul. 25, 1997 Sec. 102(e) Date Jul. 25, 1997 PCT Filed Feb. 16, 1996 PCT Pub. No. WO96/26943 PCT Pub. Date Sep. 6, 1996Compounds of formula (I) wherein R1 is hydrogen, lower alkyl, aralkyl, cycloalkyl, R3CO- or -C(R4R5)CO2R6; where R4 and R5 are each independently hydrogen or lower alkyl, or R4 and R5 taken together with the carbon atom to which they are attached form a cycloalkyl group; R3 is hydrogen or lower alkyl and R6 is hydrogen, lower alkyl, lower alkenyl or a carboxylic acid protecting group; R2 is isobutyl, 2,2-dimethyl-propyl or cyclohexyl-methyl; n is 0, 1 or 2; X is CH or N; 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 are disclosed. These compounds have valuable antibacterial activity.