Synthesis of 4, 4-Disubstituted β-Lactams by Regiospecific Electrophile-and Silver-Induced Ring Expansion of 2, 2-Disubstituted 1-Methoxycyclopropylamines
2, 2-Disubstituted 1-methoxycyclopropylamines underwent regiospecific ring expansion to 1, 4, 4-trisubstituted 2-azetidinones by N-chlorination with tert-butyl hypochlorite and subsequent rearrangement with silver tetrafluoroborate. Upon thermolysis, 4, 4-disubstituted β-lactams suffer a characteristic ring opening to afford β, γ-unsaturated carboxylic amides. The reduction of 1, 4, 4-trisubstituted 2-azetidinones with lithium aluminum hydride ...
