Combining Electronic and Steric Effects To Generate Hindered Propargylic Alcohols in High Enantiomeric Excess
作者:Vijyesh K. Vyas、Richard C. Knighton、Bhalchandra M. Bhanage、Martin Wills
DOI:10.1021/acs.orglett.7b03884
日期:2018.2.16
o-fluoro substituents results in an improvement to the reduction enantioselectivity, as does the replacement of a phenyl ring on the alkyne with a trimethylsilyl group. These effects are rationalized as resulting from a change in the steric properties of the aryl ring and the electronic properties of the alkyne which, when matched in the reduction transition state, combine within a “window” of substrate/catalyst
束缚钌-TsDPEN配合物已用于催化一系列芳基/炔酮的不对称转移氢化反应。将邻位取代基引入底物的芳基环会导致对映选择性的逆转,而引入两个邻氟取代基则会导致还原对映体选择性的提高,而取代基上的苯环也是如此。具有三甲基甲硅烷基的炔烃。这些效应是由于芳基环的空间性质和炔烃的电子性质发生变化而合理化的,这些炔烃在还原过渡态下匹配时,会在底物/催化剂匹配的“窗口”内结合,生成高分子量的产物ee。