Formation of Indoles, Dihydroisoquinolines, and Dihydroquinolines by Ruthenium-Catalyzed Heterocyclizations

Indoles, dihydroisoquinolines, and dihydroquinolines were efficiently prepared by ruthenium-catalyzed heterocyclizations of aromatic homo- and bis-homopropargyl amines/amides in the presence of an amine/ammonium base-acid pair. These regioselective 5-endo and 6-endo cyclizations most probably occur by nucleophilic trapping of key ruthenium-vinylidene intermediates.