A Chiral Chelating Diene as a New Type of Chiral Ligand for Transition Metal Catalysts: Its Preparation and Use for the Rhodium-Catalyzed Asymmetric 1,4-Addition
作者:Tamio Hayashi、Kazuhito Ueyama、Norihito Tokunaga、Kazuhiro Yoshida
DOI:10.1021/ja037367z
日期:2003.9.1
As a new type of chiral ligand, a C2-symmetric norbornadiene derivative (1R,4R)-2,5-dibenzylbicyclo[2.2.1]hepta-2,5-diene (1) was prepared and used for the rhodium-catalyzed asymmetric addition of organoboron and -tin reagents to alpha,beta-unsaturated ketones, which gave high yields of the 1,4-addition products with up to 99% enantioselectivity.
Simple Chiral Diene Ligands Provide High Enantioselectivities in Transition-Metal-Catalyzed Conjugate Addition Reactions
作者:Kazuhiro Okamoto、Tamio Hayashi、Viresh H. Rawal
DOI:10.1021/ol801931v
日期:2008.10.2
Chiral dienes possessing the bicyclo[2.2.2]octadiene framework were prepared readily through the [4 + 2] cycloaddition of ( R)-alpha-phellandrene with methyl propiolate as the key step. Diene 9, substituted with a tertiary alcohol on one of the two double bonds, is prepared in just one step from the cycloadduct and is highly effective as a chiralligand for rhodium-catalyzedasymmetricconjugate addition