Catalytic enantioselective synthesis of sterically demanding alcohols using di(2°-alkyl)zinc prepared by the refined Charette's method
作者:Manabu Hatano、Tomokazu Mizuno、Kazuaki Ishihara
DOI:10.1039/c0cc01301c
日期:——
A highly practical, catalytic enantioselective 2°-alkyl addition to aldehydes and ketones was developed. Chiral phosphoramide ligand (1) with salt-free and solvent-free di(2°-alkyl)zinc reagents prepared from (2°-alkyl)MgCl was essential.
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.
Copper-dipyridylphosphine-catalyzed hydrosilylation: enantioselective synthesis of aryl- and heteroarylcycloalkyl alcohols
作者:Shan-Bin Qi、Min Li、Shijun Li、Ji-Ning Zhou、Jun-Wen Wu、Feng Yu、Xi-Chang Zhang、Albert S. C. Chan、Jing Wu
DOI:10.1039/c2ob27040d
日期:——
hydrosilylation of a vast array of aryl cycloalkyl ketones with different ring sizes was studied systematically for the first time (up to 99% enantiomeric excess). The results demonstrated that the steric size of cycloalkyl groups has a significant influence on the reaction outcomes. The first stereoselective formation of a selection of cyclohexyl heteroaryl alcohols of up to 97% enantiopurity was realized