Direct substitution of benzylic alcohols with electron-deficient benzenethiols via π-benzylpalladium(<scp>ii</scp>) in water
作者:Hidemasa Hikawa、Mariko Toyomoto、Shoko Kikkawa、Isao Azumaya
DOI:10.1039/c5ob01717c
日期:——
nucleophilic substitution of benzylic alcohols with electron-deficient benzenethiols in water is developed. π-Benzylpalladium(II) cation complexes show high catalytic activity for S-benzylation, which provides a mechanistic alternative to the borrowing hydrogen methodology. Hammett studies on the rate constants of S-benzylation by various substituted alcohols show good correlation between log(kX/kH) and
提出了一种在水中用缺电子的苯硫醇直接亲核取代苄醇的有效且环保的方法。π-苄基钯(II)阳离子络合物对S-苄基化反应显示出高催化活性,这为借用氢法提供了一种机制选择。Hammett对各种取代醇的S-苄基化速率常数的研究表明log(k X / k H)与各个取代基的σ值之间具有良好的相关性。从斜率开始,负ρ得到的值表明过渡态中存在正电荷的积累。水在sp 3 C–O键活化和活化的Pd(II)阳离子物种的稳定化催化体系中起着重要作用。