Facile Synthesis of Polysubstituted Indolizines via One-Pot Reaction of 1-Acetylaryl 2-Formylpyrroles and Enals.

An efficient method for the synthesis of polysubstituted indolizines has been developed based on formal [4+2] annulation of 1-acetylaryl 2-formylpyrroles with enals, followed by oxidative aromatization. Pyridine-type six-membered rings were constructed in this transformation. This transition metal-free reaction features mild reaction conditions, a broad substrate scope, and excellent functional group tolerance. Notably, the formyl group is well tolerated under reaction conditions.