Intermolecular Nonreductive Alkylation of Enamides via Radical−Polar Crossover

A carbon−carbon bond construction method is disclosed which involves radical addition of α-haloesters or iodoacetonitrile to enamides. Despite the presence of tri-n-butylstannane, nonreductive addition was predominant; H-atom transfer from tin hydride was not observed. Rapid iodine atom transfer to (or electron transfer from) the radical adduct, resulting in an iminium ion intermediate and radical chain propagation, is consistent with the observed reactivity.