Intramolecular Diels−Alder Reaction of 2-Cyano-1-aza-1,3-butadienes

Abstract
It has been demonstrated that a a-cyano substituent is sufficient to activate 1-aza-1,3-butadienes with respect to the intramolecular Diels-Alder reaction. This reaction is successful for the preparation of the indolizidine and quinolizidine ring systems. The stereochemistry of the isomeric products was assigned by a careful analysis of their NMR spectral data.