Cephalosporins. I. Cephaloglycin analogs with six-membered heterocycles in the C-3 side chain.

Cephaloglycin analogs with six-membered heterocycles in the C-3 side chain have been prepared by nucleophilic substitution of 7-aminocephalosporanic acid with appropriate azine thiols followed by 7-N-acylation with phenylglycine by the mixed anhydride method. Seventeen thiols of non-substituted or substituted pyridines, pyridazines, pyrimidines, pyrazines and triazines were used as the S-nucleophiles. In general, pyridazine thiols gave cephalosporins processing good antimicrobial activity against both gram-positive and gram-negative bacteria. Among them 6-hydroxypyridazine-3-thiol gave the most active compound of this series, BB-S 118 (1f), which was significantly more active than cephalexin and cephaloglycin in vitro against gram-positive and gram negative bacteria.