Aryl Bromides as Inexpensive Starting Materials in the Catalytic Enantioselective Arylation of Aryl Aldehydes: The Additive TMEDA Enhances the Enantioselectivity
作者:Yong-Xin Yang、Yue Liu、Lei Zhang、Yan-E Jia、Pei Wang、Fang-Fang Zhuo、Xian-Tao An、Chao-Shan Da
DOI:10.1021/jo502070r
日期:2014.11.7
We used aryl bromides as inexpensive starting materials to enantioselectively arylate aldehydes in one pot. Aryl bromides readily transfer aryls to aryllithiums with n-butyllithium, successively to triarylaluminums with aluminum chloride, and then to aryltitaniums with titanium isopropoxide. Finally aryltitaniums arylate aldehydes catalyzed by (S)-H-8-BINOLTi(Oi-Pr)(2) in excellent yields and enantioselectivities. The additive TMEDA evidently suppresses the racemic background reaction promoted by LiCl generated from salt metathesis. This procedure represents a cost-effective and operationally convenient method for enantioenriched diarylmethanols.
Highly enantioselective addition of arylzinc reagents to aldehydes promoted by chiral aziridine alcohols
作者:Zuzanna Wujkowska、Szymon Jarzyński、Adam M. Pieczonka、Stanisław Leśniak、Michał Rachwalski
DOI:10.1016/j.tetasy.2016.10.005
日期:2016.12
Enantiomerically pure, chiral secondary and tertiary aziridine alcohols have proven to be highly efficient catalysts for enantioselective asymmetric additions of arylzinc species to aldehydes leading to products in high chemical yields (up to 90%) and with ee's up to 90%. The influence of the stereogenic centers located at the aziridine subunit on the stereochemical course of the reaction is discussed. (C) 2016 Elsevier Ltd. All rights reserved.
Catalytic Asymmetric Addition of an<i>in</i>-<i>situ</i>Prepared Arylzinc to Cyclohexanecarboxaldehyde: (<i>R</i>)-(+)-α-cyclohexyl-3-methoxy-benzenemethanol