Abstractmagnified imageThe Lewis base‐Lewis base bifunctional catalytic system has been developed and successfully applied to the asymmetric Friedel–Crafts alkylation of indoles with α,β‐unsaturated aldehydes. The reactions are promoted by chiral diphenylprolinol trimethylsilyl ether in the presence of triethylamine. By this protocol, optically active 3‐substituted indoles can be obtained in an organocatalytic process that is free of Lewis or protic acid in high yields with up to 98% ee. Besides, this reaction could be carried out on a gram scale without any loss in the enantioselectivity.
An Efficient Enantioselective Method for Asymmetric Friedel-Crafts Alkylation of Indoles with α,β-Unsaturated Aldehydes
作者:Liang Hong、Lei Wang、Chao Chen、Bangzhi Zhang、Rui Wang
DOI:10.1002/adsc.200800710
日期:2009.3
Abstractmagnified imageThe Lewis base‐Lewis base bifunctional catalytic system has been developed and successfully applied to the asymmetric Friedel–Crafts alkylation of indoles with α,β‐unsaturated aldehydes. The reactions are promoted by chiral diphenylprolinol trimethylsilyl ether in the presence of triethylamine. By this protocol, optically active 3‐substituted indoles can be obtained in an organocatalytic process that is free of Lewis or protic acid in high yields with up to 98% ee. Besides, this reaction could be carried out on a gram scale without any loss in the enantioselectivity.