Enantioselective Michael Addition Using Recyclable and Water-Soluble Catalysts

摘要: Significance: A catalytic enantioselective Michael addition of aldehydes and nitroalkenes using water-soluble and recyclable diarylprolinol silyl ether salts is presented. The authors obtained products 1 in high yields with excellent enantioselectivities. Benzoic acid was used to form ammonium salts with the catalyst, which enhanced the water solubility. The authors also carried out catalyst recycling experiments, and the enantioselectivity was maintained, although the activity of the catalyst dropped gradually after four cycles.