Palladium-catalyzed regioselective [3 + 2] annulation of internal alkynes and iodo-pyranoquinolines with concomitant ring opening.

A regioselective tandem synthesis of highly functionalized pyrrolo[1,2-a]quinolines has been developed through a novel strategy by palladium-catalyzed [3 + 2] annulation of iodo-pyranoquinolines and internal alkynes with subsequent ring opening. Pyranoquinoline with n-alkyl substitution at the 3-position leads to the formation of pyrrolo-acridones via [3 + 2] annulations/ring opening and successive intramolecular cross-aldol condensation.