Asymmetric direct aldol reaction catalyzed by an L-prolinamide derivative: considerable improvement of the catalytic efficiency in the ionic liquid

The asymmetric direct aldol reactions of a wide scope of aldehydes with unmodified ketones in the presence of 20 mol% (S, S, S)-pyrrolidine-2-carboxylic acid (2'-hydroxyl-1',2'-diphenylethyl)- amine ( 1) were performed in ionic liquids; aldol products with 91 to >99% ees for aromatic aldehydes and 99% ees for alphatic aldehydes were offered by the present procedure.