Stereoselective synthesis of spirocyclic-pyrrolo-quinolinones via cascade [4+2] annulation of indole-based chalcones and activated carbonyl compounds

A straightforward and stereoselective approach has been developed for the construction of pyrroloquinoline derivatives through the reaction of indole-derived chalcones with diverse Michael acceptors, including alkylidene esters/ketones and vinylidene indanones. The transformation proceeds smoothly under mild conditions, displaying good functional group tolerance. Mechanistically, the process involves a [4+2] aza-Michael addition followed by intramolecular cyclization, affording the desired products in good to excellent yields.