NOVEL ANTIBACTERIAL COMPOUNDS

摘要

Pharmacologically acceptable esters, ethers and carbamoyl N-alkylates derive d from compounds represented by general formula (Ia), and pharmacologically acceptable salts of the same, which exhibit an excellent antibacterial activity and are useful in the treatment or prevention of infectious disease s, wherein R1 is hydrogen or methyl; R2a is hydrogen, a hydroxyl-protecting gro up or methyl; R3 is hydrogen or a hydroxyl-protecting group; R4a is hydrogen or optionally protected hydroxyl; R5 is hydrogen or a hydroxyl-protecting group ; and X is methylene or sulfur.