An investigation of the scope of the 1,7-electrocyclization of α,β:γ,δ-conjugated azomethine ylides

摘要: Substituents on the diene component have little influence periselectivity of cyclizations α,β:γ,δ-conjugated azomethine ylides, with 1,7-electrocyclizations predominating. In some cases, subtle changes to these substituents can, however, product formed, through their effect relative energies transition states for 1,5- (6π) and 1,7-electrocyclization (8π) processes. The most striking in occur phenylethenyl-substituted ylides 3d–f, which can give either a pyrroline 4d,f or dihydrobenzazepine 6e, depending upon alkene configuration.