期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 138, 期 3, 页码 734-737出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.5b11402
关键词
-
资金
- Fond de la Recherche Scientifique de Belgique (F.R.S.-FNRS) [2.5020.11]
- EPSRC [EP/E052185/1, EP/K03927X/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/E052185/1, EP/D501725/1, EP/K03927X/1] Funding Source: researchfish
The activation of the S-N(2) reaction by systems is well documented in textbooks. It has been shown previously that this is not primarily due to classical (hyper)conjugative effects. Instead, pi-conjugated substituents enhance favorable substrate-nucleophile electrostatic interactions, with electron-withdrawing groups (EWG) on the sp(2) system leading to even stronger activation. Herein we report computational and experimental results which show that this activation by sp2 EWG-substitution only occurs in a fairly limited number of cases, when the nucleophile involves strong electrostatic interactions (usually strongly basic negatively charged nucleophiles). In other cases, where bond breaking is more advanced than bond making at the transition state, electrophile-nucleophile electrostatic interactions are less important. In such cases, (hyper)conjugative electronic effects determine the reactivity, and EWG-substitution leads to decreased reactivity. The basicity of the nucleophile as well as solvent effects can help to determine which of these two regimes occurs for a given electrophile.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据