Enantioselective Friedel–Crafts Alkylation of Aniline Derivatives with 4-Arylidenepyrrolidine-2,3-diones Catalyzed by Chiral Cu(II) Complex Bearing Binaphthyl-Proline-Imidazoline-type Chiral Ligands

Cu(II)-complex-catalyzed enantioselective Friedel-Crafts alkylation of aniline derivatives with 4-benzylidenepyrrolidine-2,3-dione-type electrophiles was enabled, and the desired products were obtained with up to 96% ee. Both <i>N</i>-mono- and <i>N</i>,<i>N</i>-dialkylated anilines and related compounds could be used as nucleophiles, and the reaction at gram scale also proceeded readily, providing the desired product without the loss of enantiomeric excess. The high enantioselectivity of the reaction relied on the unique structure of the chiral catalysts, which allowed the effective and stereofacially selective activation of the substrates. X-ray diffraction experiment confirmed the absolute configuration of the product, and stereofacial selection of the reactions was deduced based on this result.