Asymmetric synthesis of CF3- and indole-containing tetrahydro-β-carbolines via chiral spirocyclic phosphoric acid-catalyzed aza-Friedel–Crafts reaction

Abstract

An enantioselective aza-Friedel–Crafts alkylation reaction of indoles with 1-trifluoromethyl-3,4-dihydro-β-carbolines catalyzed by a chiral spirocyclic phosphoric acid has been realized. This methodology provides a facile route to 1-trifluoromethyl-1-indole-substituted tetrahydro-β-carbolines featuring a CF₃-containing quaternary stereocenter in considerable yields and good enantioselectivities.