Asymmetric Friedel−Crafts Reaction of Indoles with Imines by an Organic Catalyst
作者:Yong-Qiang Wang、Jun Song、Ran Hong、Hongming Li、Li Deng
DOI:10.1021/ja062700v
日期:2006.6.1
In this communication, we report an asymmetric Friedel-Craftsreaction of indoles with imines catalyzed by a bifunctional cinchona alkaloid catalyst. This is the first efficient organocatalytic asymmetric Friedel-Craftsreaction of indoles with imines. This reaction is operationally simple and, unprecedentedly, affords high enantioselectivity for a wide range of indoles and both aryl and alkyl imines
9-Thiourea Cinchona alkaloid supported on mesoporous silica as a highly enantioselective, recyclable heterogeneous asymmetric catalyst
作者:Peng Yu、Jing He、Canxiong Guo
DOI:10.1039/b800640g
日期:——
A readily recycled and regenerated heterogeneous catalyst of 9-thiourea epi-quinine supported on mesoporous silica exhibits enhanced enantioselectivity (up to 99.2%) in the asymmetric Friedel-Crafts reaction of imines with indoles.
Stepwise fabrication and architecture of heterogeneous 9-thiourea epiquinine catalyst with excellent enantioselectivity in the asymmetric Friedel–Crafts reaction of indoles with imines
作者:Peng Yu、Jing He、Lan Yang、Min Pu、Xiaodan Guo
DOI:10.1016/j.jcat.2008.09.006
日期:2008.11
Heterogeneous 9-thiourea epiquinine catalysts are prepared by covalently anchoring 9-(3,5-bis(trifluoromethyl)phenylthiourea)epiquinine on mesoporous silica surfaces via mercapto linker. It is found that 9-thiourea epiquinine moieties are located comparably on the interior and exterior surfaces of SBA-15 while preferentially on the exterior surface of MCM-41. The heterogeneous 9-thiourea epiquinine are applied as catalysts in the asymmetric Friedel-Crafts reaction of indoles with imines. SBA-15 supported 9-thiourea epiquinine, with more catalytic sites inside the channels, is found more chemselective and enantioselective than the counterpart supported on MCM-41. The effects of solvents and molecule dimensions of both substrates on the reaction effectiveness and selectivity are also discussed. (C) 2008 Elsevier Inc. All rights reserved.