Asymmetric Friedel–Crafts Alkylations of Indoles with Ethyl Glyoxylate Catalyzed by (S)-BINOL-Titanium(IV) Complex: Direct Access to Enantiomerically Enriched 3-Indolyl(hydroxy)acetates
EnantioselectiveFriedel–Craftsalkylation reactions of a variety of indoles with ethyl glyoxylate, catalyzed by a chiral (S)-BINOL-Ti(IV) complex (10 mol %), are reported. The corresponding ethyl 3-indolyl(hydroxy)acetates were formed in good yields and with high enantiomeric excess (up to 96 %). When methyl pyruvate or p-chlorophenylglyoxal was used, the bisindole compound was obtained in excellent