Copper-Free Asymmetric Allylic Alkylation with Grignard Reagents
作者:Olivier Jackowski、Alexandre Alexakis
DOI:10.1002/anie.201000577
日期:2010.4.26
Open wide and say AAA: The copper‐free asymmetric allylicalkylation reaction of Grignardreagents, catalyzed by N‐heterocyclic carbenes, is reported for allyl bromide derivatives. This reaction offers good enantioselectivity and good to excellent γ regioselectivity, particularly for the formation of quaternary chiral centers (see scheme; Mes=mesityl).
张开嘴说AAA:据报道,N-杂环卡宾催化了格氏试剂的无铜不对称烯丙基烷基化反应,是烯丙基溴衍生物的反应。该反应提供了良好的对映选择性和良好的至优异的γ区域选择性,特别是对于形成四元手性中心(参见方案; Mes =甲磺酰基)。
Copper-Catalyzed Asymmetric Allylic Substitution of Allyl Phosphates with Aryl- and Alkenylboronates
The asymmetricallylicsubstitution of allylphosphates with aryl‐ and alkenylboronates catalyzed by a copper/N‐heterocyclic carbene complex was developed and the γ‐substitution products were obtained with high enantioselectivity (see scheme). To account for the observed influence of the reaction parameters a possible catalytic cycle for this process was proposed.
Chiral N-Heterocyclic Carbene−Copper(I)-Catalyzed Asymmetric Allylic Arylation of Aliphatic Allylic Bromides: Steric and Electronic Effects on γ-Selectivity
作者:Khalid B. Selim、Hirotsugu Nakanishi、Yasumasa Matsumoto、Yasutomo Yamamoto、Ken-ichi Yamada、Kiyoshi Tomioka
DOI:10.1021/jo102386s
日期:2011.3.4
sterically tuned to improve γ-selectivity in copper(I)-catalyzed asymmetric allylic arylation of aliphatic allylic bromides with several aryl Grignardreagents. High γ-selectivity was realized when either the aryl group of the Grignardreagent or the aryl group on the N-substituent of the carbene ligand was electron-deficient or when either the carbene ligand or allylic bromide was bulky. The results indicated
Enantiomeric purity of 3-phenyl-4,4-dimethyl-1-pentene. Chemical interrelation between the maximum rotations of .alpha.-tert-butylphenylacetic acid and .beta.-tert-butyl-.beta.-phenylpropionic acid