Novel bifunctional bifunctional L-prolinamide derivatives as highly efficient organocatalysts for asymmetric nitro-Michael reactions

A series of novel bifunctional L-prolinamide derivatives was synthesised, of which (S)-N-((S)-2-oxo-1-phenyl-2-(tritylamino)ethyl)pyrrolidine-2-carboxamide 6 was found to be the most effective catalyst in terms of both the yield and stereoselectivity for the nitro-Michael reaction of aldehydes to nitroalkenes. Under these optimized reaction conditions, 17 corresponding novel nitro-Michael addition adducts had high yields (up to 94%) and showed excellent diastereoselectivity (up to 99:1 dr) and enantioselectivity (up to 98 ee) under mild reaction conditions. (C) 2016 Elsevier Ltd. All rights reserved.