The direct aldol reactions catalyzed by chiral dendritic catalysts derived from N-prolylsulfonamide gave the corresponding products in high isolated yields (up to 99%) with excellent anti diastereoselectivities (up to >99:1) and enantioselectivities (up to >99% ee) in water. In addition, catalyst 1e may be recovered by precipitation and filtration and reused for at least five times without loss of catalytic activity.

A new series of 4,4'-disubstituted prolines (1a-h) has been developed and tested as organocatalysts in the direct catalytic asymmetric aldol reaction of several aliphatic ketones with aldehydes. Catalyst 1g affords the best enantioselectivities for this transformation. The reaction was carried out in DMF using a catalyst loading of 10 mol % at À10 8C to give the aldol products in up to 97 % ee for acetone. In the cases of cyclohexanone and cyclopentanone, the corresponding anti-products were obtained in 94 % ee.