Biscinchona alkaloids as highly efficient bifunctional organocatalysts for the asymmetric conjugate addition of malonates to nitroalkenes at ambient temperature
摘要:
The novel bifunctional bisalkaloids have been developed as highly efficient catalysts for the asymmetric conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes with low catalyst loading (1 mol %) at ambient temperature, providing the products with excellent enantioselectivities (up to 97% ee). Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
progress has been made toward the development of metal-free catalysts of enantioselective transformations, yet the discovery of organic catalysts effective at low catalyst loadings remains a major challenge. Here we report a novel synergistic catalyst combination system consisting of a peptide-inspired chiral helical (thio)urea oligomer and a simple tertiary amine that is able to promote the Michael reaction