Highly enantioselective tandem cyclopropanation/Wittig reaction of α,β-unsaturated aldehydes with arsonium ylides catalyzed by recyclable dendritic catalyst
作者:Yun-Hui Zhao、Chang-Wu Zheng、Gang Zhao、Wei-Guo Cao
DOI:10.1016/j.tetasy.2008.02.022
日期:2008.4
A novel tandem cyclopropanation/Wittig reaction of alpha,beta-unsaturated aldehydes with arsonium ylides using a chiral 2-trimethylsilanyloxy-methyl-pyrrolidine-based dendritic catalyst is described. Good yields (up to 86%), and high diastereoselectivities (up to dr = 99: 1) and enantioselectivities (up to 99% ee) were obtained under simple and mild reaction conditions. The catalyst can be recycled without any loss in activity. (c) 2008 Elsevier Ltd. All rights reserved.
Organocatalytic asymmetric cyclopropanation of α,β-unsaturated aldehydes with arsonium ylides
作者:Yun-Hui Zhao、Gang Zhao、Wei-Guo Cao
DOI:10.1016/j.tetasy.2007.10.007
日期:2007.10
A novel organocatalytic asymmetric cyclopropanation of alpha,beta-unsaturated aldehydes with arsonium ylides using diphenylprolinol silylether as a catalyst is described. A variety of chiral cyclopropyl aldehydes are obtained in moderate to good yields with up to 99:1 dr (diastereomeric ratio) and 99% ee under simple and mild reaction conditions. (c) 2007 Elsevier Ltd. All rights reserved.