PREPARATION OF BETA-LACTAMS FROM BETA-HYDROXY AMIDES, AND ANNULATION OF N-MALONYL BETA-LACTAMS BY MANGANESE(III) ACETATE-PROMOTED FREE-RADICAL CYCLIZATION AND BY ALDOL CYCLIZATION

beta-Lactams are formed from beta-hydroxy amides by base-promoted cyclization of the beta-methylsulfonoxyamide. In the system studied, this amide-based mesylate cyclization proceeded in high yields, whereas the analogous beta-chloroamide afforded only the alpha,beta-unsaturated amide. Also, two new methods of synthesizing carbacephams by annulation of malonate-substituted beta-lactams were demonstrated. The first was a manganese(III) acetate-promoted oxidative free radical cyclization. The second was a spontaneous aldol cyclization of an intermediate aldehyde generated by ozonolysis of an alkene.