Enantioselective Friedel–Crafts C2-alkylation of 3-substituted indoles with trifluoropyruvates and cyclic N-sulfonyl α-ketiminoesters

Abstract

Enantioselective Friedel–Crafts C2-alkylation reactions of 3-substituted indoles with trifluoropyruvates and cyclic N-sulfonyl α-ketiminoesters were developed by using the complexes of Cu(OTf)₂ or Zn(OTf)₂ with chiral bisoxazoline ligands. A range of chiral indole-containing trifluoromethylated α-hydroxyesters and cyclic α-aminoesters bearing quaternary stereogenic centers were afforded in good yields and excellent enantioselectivities (up to 99% ee) under mild conditions.