SYNTHESES OF NEW ISOCEPHEMS AND ISODETHIAOXACEPHEMS AS ANTIMICROBIAL AGENTS

The cis-configurated isocephem 26 as well as isodethiaoxacephems 21 an d 33 were synthesized (Schemes 4 and 5). The key step involves chlorin ation of the corresponding carbanions of 23, 18, and 31 with CF3SO2Cl followed by internal alkylation. beta-Lactams 3, 21, 26, and 33 were f ound to possess biological activity against several pathogenic microor ganisms in vitro. Electronic activation of the lactam moiety in isodet hiaoxacephem 33 remarkably enhanced its biological activity.