Cephem compounds and processes for preparation thereof

摘要

The invention relates to novel cephem compounds, of high antimicrobial activity, of the formula <IMAGE> wherein R1 is amino or protected amino, R2 is lower alkyl substituted with 1 to 3 halogen atoms, R3 is thiadiazolylthiomethyl which may be substituted with lower alkyl, or tetrazolylthiomethyl which may be substituted with lower alkyl or lower alkenyl, and R4 is carboxy or protected carboxy, and a pharmaceutically acceptable salt thereof.