Free-Radical Cyclization in the Synthesis of a l-Aza-5-silabicyclo[5.2.0]nonan-9-one, aSilicon-Containing beta-Lactam

摘要

More than 50 years after the discovery of the antibacterial effect of penicillin in man, beta-lactam antibiotics are still under active investigation by organic chemists. New, more selective antibiotics, or antibiotics with a broad spectrum of action,are needed since the frequency of antimicrobial-resistant infections has increased in both the hospital and the community. Intense investigations have resulted in the discovery of several natural and synthetic biologically-active substances containing the beta-lactam ring, including cephalosporins, carbapenems, penems, oxa- and carbacephems as well as monobac-tams, nocardicin derivatives, clavams, or other spi-ranic or multicyclic ring systems. Most of the variations have been introduced by keeping the beta-lactam moiety intact but changing the atoms, functional groups and the size of the B ring.