Ruthenium-Catalyzed Oxidative Formal Aza-Diels-Alder Reaction: Enantioselective Synthesis of Benzo[a ]quinolizine-2-ones

A method for preparation of thermodynamic (4R,11bS)-benzo[a]quinolizine-2-one derivatives in good enantio- and diastereoselectivity by a one-pot oxidative formal aza-Diels−Alder reaction of 1,2,3,4-tetrahydroisoquinolines and α,β-unsaturated ketones is described. The reaction proceeds via tandem Ru-catalyzed amine dehydrogenation using TBHP as the oxidant and a chiral thiourea-catalyzed formal aza-[4+2] cycloaddition, providing a step-economical strategy for synthesis of valuable heterocyclic products.