Lewis Acid Catalyzed Formation of Tetrahydroquinolines via an Intramolecular Redox Process

Polycyclic tetrahydroquinolines were prepared by an efficient Lewis acid catalyzed 1,5-hydride shift, ring closure sequence. Gadolinium triflate was Identified as a catalyst that Is superior to scandium triflate as well as other Lewis acids. An approach toward a catalytic enantioselective variant Is also described.