Chiral Calix[4]arenes-Bearing Prolinamide Functionality as Organocatalyst for Asymmetric Direct Aldol Reactions in Water

The chiral calix[4]arene derivative (6) bearing an L-prolinamido group has been designed and proved to be a water compatible efficient organocatalysts for a direct enantioselective aldol reaction. Compound 6 catalyzes the aldol reaction of cyclohexanone and a variety of aromatic aldehydes yielding anti-aldol products in high yield with enantioselectivities of up to 93% and diastereoselectivity of up to 95:5.