Enantioselective Friedel-Crafts alkylation for synthesis of 2-substituted indole derivatives

An efficient catalytic asymmetric intermolecular C2 Friedel-Crafts alkylation reaction between N-methyl skatole and beta,gamma-unsaturated alpha-ketoesters has been realized by a chiral N,N'-dioxide-Ni(II) complex. The corresponding indole derivatives were obtained in good yield (up to 96%) with excellent enantioselectivities (up to 99% ee) under mild reaction conditions.