Chiral Bronsted acid catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with alpha,beta-unsaturated ketones: short access to optically active 2-and 3-substituted indole derivatives

The asymmetric Friedel-Crafts alkylation reaction of indoles with alpha,beta-unsaturated ketones catalyzed by chiral phosphoric acid is reported. A wide range of indoles and 4,7-dihydroindoles were allowed to react with alpha,beta-unsaturated ketones to give the corresponding 1,4-adducts in good to high chemical yields and with excellent enantioselectivities.