AgAsF6/Sm(OTf)3 Promoted Reversal of Enantioselectivity for the Asymmetric Friedel−Crafts Alkylations of Indoles with β,γ-Unsaturated α-Ketoesters

Abstract

The first example of central metal controlled reversal of enantioselectivity in asymmetric Friedel-Crafts alkylation of indoles and beta,gamma-unsaturated alpha-ketoesters has been developed. Using the same chiral starting material derived N,N'-dioxides 1a and 1b as ligands, various indole esters 4 were obtained in good to excellent yields and enantioselectivities. The reaction also featured mild reaction conditions and remarkably low catalyst loading (down to 0.01 mol %).