A total stereospecific route to α-alkylidene-γ-lactams

A new efficient γ-lactams 4 synthesis was achieved by two successive reactions: alkylation of nitroalkane anions with dimethyl α-(bromomethyl) fumarate 1 leading to the formation of (E)-1-alkyl-2,3-dimethoxycarbonyl butadienes 3a,b resulting of tandem alkylation–elimination (dehydronitration) processes, followed by an intramolecular cyclization on addition of primary amine.