对映体纯底物的催化反应形成新的手性元素可能会导致催化剂的一种对映体(匹配对)比另一种对映体(错配对)具有更高的非对映选择性。使用导致形成新的立体中心的动力学解析程序的文献示例来研究匹配反应更快的假设。除 15 个示例中的一个例外外,选择性因子 ( s = k fast / k Slow ) = k匹配/ k不匹配。提出了一种估计快速匹配反应与相应的慢速错配反应的相对速率的模型。该模型还提供了对所研究的动力学拆分程序中显示的选择性基础的深入了解。
对映体纯底物的催化反应形成新的手性元素可能会导致催化剂的一种对映体(匹配对)比另一种对映体(错配对)具有更高的非对映选择性。使用导致形成新的立体中心的动力学解析程序的文献示例来研究匹配反应更快的假设。除 15 个示例中的一个例外外,选择性因子 ( s = k fast / k Slow ) = k匹配/ k不匹配。提出了一种估计快速匹配反应与相应的慢速错配反应的相对速率的模型。该模型还提供了对所研究的动力学拆分程序中显示的选择性基础的深入了解。
Highly Enantioselective Reaction of α-Selenoorganolithium Compounds with Chiral Bis(oxazoline)s and Preparation of Enantioenriched Benzylidencyclohexanes
The enantioselective reaction of α-seleno carbanions derived from bis(phenylseleno)acetal and bis(2-pyridylseleno)acetal in the presence of bis(oxazoline)s with various electrophiles gave products with high enantioselectivity. The enantioselective reaction of α-lithio benzyl 2-pyridyl selenide gave the products with stereochemistry reverse to that obtained in the reaction of α-lithio benzyl phenyl
Studies in asymmetric olefinations — the synthesis of enantiomerically pure allylidene, alkylidene, and benzylidene cyclohexanes
作者:Stephen Hanessian、Serge Beaudoin
DOI:10.1016/0040-4039(93)88008-7
日期:1992.12
of alkyl cyclohexanones with topologically unique bicyclic phosphonamides derived from the C2 symmetrical (R,R)- and (S,S)-N,N′-dimethyl 1,2-trans-cyclohexane diamine leads to enantiomericallypureallylidene and benzylidene alkylcyclohexanes.
diastereomeric mixture. Each diastereomer obtained had highopticalpurity. The reaction of the α-seleno carbanion derived from the bis(phenylseleno)acetal also showed high enantioselectivity. The stereospecific elimination of the isolated diastereomers on treatment with methanesulfonyl chloride and triethylamine afforded axially chiral benzylidenecyclohexanes with high enantioselectivities up to 99% ee.