Cephem compounds

摘要

The invention relates to new cephem compounds of high antimicrobial activity, the compounds having the formula <IMAGE> wherein R1 is amino or a protected amino group R2 is a saturated 4 to 8-membered heteromonocyclic group containing one sulfur atom; R3 is carboxy or a protected carboxy group and R4 is hydrogen, lower alkyl, or a group of the formula: -CH2R4a where R4a is acyloxy a heterocyclicthio group which may have suitable substituents or pyridinio which may have suitable substituents with the proviso that R3 is COO-when R4a is pyridinio which may have suitable substituents.