Diarylprolinol Silyl Ether Salts as New, Efficient, Water-Soluble, and Recyclable Organocatalysts for the Asymmetric Michael Addition on Water

摘要

The organocatalytic asymmetric Michael reaction of aldehydes to nitroolefins is a key transformation in organic synthesis. Many chiral organocatalysts have been developed to exhibit high activities and enantioselectivities for this cornerstone transformation in recent years. However, a major problem associated with these organocatalytic systems is that high catalyst loading (normally 10-30 mol %) and large excess amounts of Michael donors (up to 10 equiv of aldehydes) are generally required for the reactions to be completed in reasonable time scales with good enantioselectivity.