Organocatalytic Asymmetric Nucleophilic Addition of Indoles to Imines

Significance

The authors report the first organocatalytic asymmetric nucleophilic addition reaction of indoles with imines. Bifunctional 9-thiourea-substituted cinchona alkaloids have recently been used for different enantioselective C-C bond formation reactions. Here the authors have found the quinine-derived thiourea catalyst 1 to be an effective catalyst for the reaction of indoles with imines. With 10 mol% of catalyst 1 good to high yields (85-98%) and enantioselectivities (86-96%) are obtained for different substituted indoles with different aryl and alkyl imines.