X=Y-ZH Systems as Potential 1,3-Dipoles. Part 26. 1,5-Electrocyclisation and Tandem 1,5-Electrocyclisation-Aldol Type Condensation Processes in Imines.

Article abstract of DOI:10.1016/S0040-4020(01)81969-4

A 1,2-prototropy route and an iminium ion route to vinyl azomethine ylides are described.In both cases the vinyl azomethine ylides undergo 1,5-electrocyclisation to dihydropyrroles.In the former case the 1,5-electrocyclisation is solvent sensitive and completes with a prototropic process giving the imine of an α,β-unsaturated α-amino ester.The mechanism and solvent sensivity are discussed.In the latter case the dihydropyrrole reacts further with aldehydes via an aldol type condensation.