Chiral sterically congested phosphane-amide bifunctional organocatalysts in asymmetric aza-Morita-Baylis-Hillman reactions of N-sulfonated imines with methyl and ethyl vinyl ketones

摘要

A series of chiral sterically congested phosphane-amide bifunctional Lewis bases L1-L3 have been successfully synthesized and their application in asymmetric aza-Morita-Baylis-Hillman (aza-MBH) reactions of N-sulfonated imines with activated olefins such as methyl and ethyl vinyl ketone has been investigated under mild conditions. The corresponding aza-MBH adducts can be obtained in good-to-excellent yields (up to 98%) and moderate-to-good enantioselectivities (up to 91 or 93 % ee) in dichloromethane at room temperature (20 degrees C) with these novel chiral bifunctional phosphane Lewis bases.