Enantioselective Friedel−Crafts Alkylation Reactions Catalyzed by a Chiral Nonracemic <i>C</i>₂-Symmetric 2,2‘-Bipyridyl Copper(II) Complex

Enantioselective Friedel−Crafts alkylation reactions of a series of substituted indoles with methyl trifluoropyruvate, catalyzed by a chiral nonracemic C2-symmetric 2,2‘-bipyridyl copper(II) triflate complex, are described. The corresponding 3,3,3-trifluoro-2-hydroxy-2-indole-3-yl-propionic acid methyl esters were formed in good yield and in high enantiomeric excess (up to 90%). This is the first report of the use of a chiral nonracemic 2,2‘-bipyridyl ligand in catalytic and enantioselective Friedel−Crafts alkylation reactions. The structural characterization of a copper(II) chloride complex of the chiral 2,2‘-bipyridyl ligand by X-ray crystallography is also presented.