Chiral Phosphoric Acid Catalyzed Highly Enantioselective Friedel-Crafts Alkylation Reaction of C3-Substituted Indoles to β,γ-Unsaturated α-Ketimino Esters

A highly enantioselective C2 Friedel-Crafts alkylation reaction of 3-substituted indoles to beta,gamma-unsaturated a-ketimino esters has been developed. This reaction was efficiently catalyzed by a chiral phosphoric acid catalyst. The corresponding C2-substituted indole derivatives, bearing an a-ketimino ester motif, were obtained in moderate to high yields (up to 93%) and with high enantioselectivities (up to >99% ee).