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

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