Enhanced Activity and Stereoselectivity of Polystyrene-Supported Proline-Based Organic Catalysts for Direct Asymmetric Aldol Reaction in Water

Several polystyrenesupported proline dipeptides and a prolinamide derivative were prepared by thiol–ene coupling. These materials were used as catalysts for the direct asymmetric aldol reaction in water, and results compared with unsupported catalysts in water. Such an approach gave more active or stereoselective catalysts compared to the unsupported compounds, showing that our immobilization procedure may be useful to develop catalytic materials with enhanced performance. Moreover, these catalysts can be recovered and reused for at least nine times without loss of activity or can be easily regenerated when their activity has decreased. © WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009