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
作者:Lei Zhang、Myoung-Mo Lee、Soo-Mi Lee、Jihye Lee、Maosheng Cheng、Byeong-Seon Jeong、Hyeung-geun Park、Sang-sup Jew
DOI:10.1002/adsc.200900787
日期:2009.12
e with C(9S)-aminodihydroquinine or C(9R)-aminodihydroquinidine and successively applied to the Michael addition of dimethyl malonate to nitroolefins as very efficient chiral Lewis acid bifunctionalorganocatalysts (up to >99% ee).