Synthesis of Aza Polycyclic Compounds Derived from Pyrrolidine, Indolizidine, and Indole via Intramolecular Diels−Alder Cycloadditions of Neutral 2-Azadienes

Abstract

A method for the preparation of novel oxaza and diaza polycyclic 9-oxa-4-azaphenanthrene, 5H-pyrido[2,3-a]pyrrolizine, 5H,6H-pyrido[3,2-g]indolizine, and 5H,6H-indeno[2,1-a]indole is described, based on tandem reactions: aza-Wittig reaction of N-vinylic phosphazenes with functionalized aldehydes and an intramolecular aza-Diels-Alder reaction.