Organocatalyzed Friedel-Craft-type reaction of 2-naphthol with beta,gamma-unsaturated alpha-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 beta,gamma-unsaturated alpha-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%). (C) 2008 Elsevier Ltd. All rights reserved.