Multicomponent Reactions of Phosphines,Enynedioates and Cinnamaldimines Give γ‐Lactams with a 1,3,5‐Hexatriene Moiety for Facile 6π Electrocyclization: Access to Oxindoles,Isatins and Isoxazolinones

Multicomponent reactions of phosphines, enynedioates and cinnamaldimines generated 3‐phosphorus ylide γ‐lactams having a 1,3,5‐hexatriene moiety with low activation energy barrier for 6π electrocyclization, through initial formation of 1,3‐dipoles from the α(δ′)‐Michael addition of phosphines to enynedioates. The reactive 1,3‐dipoles underwent addition to cinnamaldimines, lactamization, 6π electrocyclization and oxidation to give 3‐phosphorus ylide oxindoles as platform molecules toward isatins and isoxazolinones. The key step, 6π electrocyclization, was further examined by a kinetic and a computational study.