HETEROCYCLIC SYNTHESIS BY ELECTROCYCLIZATION OF EXTENDED DIPOLES: A NOVEL ACCESS TO THE INDOLIZINE AND QUINOLIZINE SYSTEMS

Article abstract of DOI:10.1016/S0040-4039(01)93807-9

On thermal activation α-butenynyl substituted pyridine-N-oxides 4 undergo a multistep rearrangement affording 4-oxo-4H-quinolizines (8) and 2-acylindolizines (9).In the geometrical isomeriziation of E-4 to Z-4 annulated isoxazolidines (7) are involved as unstable intermediates.