A facile synthesis of 2-exo-methylenepenam; a potent intermediate for syntheses of new β-lactamase inhibitors
Abstract
A convenient synthesis of 2-exo-methylenepenams 1 is performed by reductive cyclization of allenecarboxylates 8 in a BiCl3/Zn bimetal redox system; subsequent manipulation of the 2-exo-methylene moiety of 1 opens new entries to β-lactam antibiotics and/or β-lactamase inhibitors.