Enantioselective ring opening of epoxides with silicon tetrachloride in the presence of a chiral lewis base: Mechanism studies
Enantioselective ring opening of epoxides with silicon tetrachloride in the presence of a chiral lewis base: Mechanism studies
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DOI：
10.1002/adsc.200600551
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发表时间：
2007-03-01
影响因子：
5.4
通讯作者：
Wilson, Tyler W.
中科院分区：
文献类型：
--
作者：
Denmark, Scott E.;Barsanti, Paul A.;Wilson, Tyler W.
在手性磷酰胺的催化下，以四氯化硅为原料（环烯烃和非环烯烃）的中环氧化合物对映选择性开环，得到对映体富集的氯丙烷，收率高。本文描述了旨在阐明对映体选择性的机制基础和起源的实验。通过对试剂（SiCl4）和催化剂[(R)-1]的负载和化学计量学研究，可以确定每个SiCl4只传递一个氯离子，并且在反应过程中反应物质的性质不会改变。动力学研究和不对称扩增实验表明，在决定立体化学的过渡结构中，可能有不止一个催化剂分子与SiCl4结合。
The enantioselective ring opening of mesoepoxides (from both cyclic and acyclic olefins) with silicon tetrachloride under catalysis by chiral phosphoramides affords enantiomerically enriched chlorohydrins in excellent yields. Experiments designed to elucidate the mechanistic foundation and origins of enantioselectivity are described. From studies on the loading and stoichiometry of the reagent (SiCl4) and the catalyst [(R)-1] it was established that only one chloride per SiCl4 is delivered and that the nature of reactive species does not change over the course of the reaction. Kinetic studies together with asymmetric amplification experiments have suggested that more than one catalyst molecule may be bound to SiCl4 in the stereochemistry-determining transition structure.