Oxidative [4+2] Annulation of Pyrrole-2-carbaldehyde Derivatives with o-Hydroxyphenyl Propargylamines: Syntheses of 5,6,7-Trisubstituted Indolizines.

A base promoted oxidative [4+2] annulation of pyrrole-2-carbaldehyde derivatives with o-hydroxyphenyl propargylamines for the synthesis of highly substituted indolizines has been developed. Using DBN as base, a broad range of 5,6,7-trisubstituted indolizines have been prepared in good to excellent yields under mild conditions, and many useful functional groups can be tolerated.