文摘
An enantioselective synthesis of 2-(3-indolyl)chromane scaffolds is described. With a bifunctional primary amine-thiophosphinamide catalyst incorporating (1R,2R)-1,2-diphenylethane-1,2-diamine, good yields and high levels of enantioselectivity (96–>99% ee) were achieved. The synthesis proceeded through organocatalyzed cascade Michael/hemiketalization followed by BF3·Et2O promoted Friedel–Crafts alkylation reaction.