Organocatalyzed Friedel–Craft-type reaction of 2-naphthol with b,c-unsaturated a-keto ester to form novel optically active naphthopyran derivatives

A novel bifunctional thiourea–tertiary-amine-catalyzed enantioselective Friedel–Craft-type addition reaction of 2-naphthol with b,c-unsaturated a-keto ester was developed. Subsequent dehydration of the reaction adducts with a catalytic amount of concentrated H2SO4 in a one-pot fashion readily afforded a series of new optically active naphthopyran derivatives with moderate to good yields (up to 91%) and enantioselectivities (up to 90%).