SYNTHESES OF THE FIRST SELENIUM-CONTAINING BICYCLIC BETA-LACTAMS AS POTENT ANTIMICROBIAL AGENTS

Syntheses of the cis-configurated isodethiaselenapenam 5 (Scheme I) as well as the isodethiaselenacephems 29 and 31 (Scheme 2) were accompli shed, in which the key step involved addition of Se to the correspondi ng carbanions of 1, 25, and 27 followed by internal alkylation. beta-L actams 29 and 31 were found to possess biological activity against sev eral pathogenic microorganisms in vitro. The electronic activation of the lactam moiety in the isodethiaselenacephem 31 and the correspondin g isocephem 33 remarkably enhanced their biological activity. Isodethi aselenacephem 31 was more toxic than isocephem 33 in experimental anim als.