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
Pj. Crocker et al., 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, Heterocycles, 40(2), 1995, pp. 691-716
beta-Lactams are formed from beta-hydroxy amides by base-promoted cycl
ization 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 a
mide. 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 ald
ehyde generated by ozonolysis of an alkene.