INTERMEDIATE FOR SYNTHESIZING VINYLPYRROLIDINONECEPHALOSPORIN HAVING BASIC SUBSTITUENT

摘要

PROBLEM TO BE SOLVED: To obtain an intermediate for synthesizing new cephalosporin derivatives having antibacterial activity especially against MRSA and Pseudomonas aeruginosa, therefore useful as antibiotics. SOLUTION: This compound is represented by formula (IIIa), being an intermediate for synthesizing cephalosporin derivatives of formula (I) [X is N; R1 is H; R2 is a group of formula (II); R3 is H; and R4 is H], readily hydrolyzable esters thereof, pharmaceutically acceptable salts thereof, and hydrates of the above esters or salts.