Debrominations of <i>vic</i>-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications
作者:Timothy S. Butcher、Feng Zhou、Michael R. Detty
DOI:10.1021/jo9713363
日期:1998.1.1
Debrominations of vic-dibromides with diaryl tellurides 1-4 and di-n-hexyl telluride (9) are described. A mechanistic explanation of the debromination is offered which accounts for several key experimental observations: (1) the reaction is highly stereoselective with erythro-dibromides giving trans-olefins and threo-dibromides giving cis-olefins, (2) the reaction is accelerated by more electron-rich
描述了用二芳基碲化物1-4和二正己基碲化物(9)对vic-二溴化物进行脱溴。提供了脱溴机理的解释,这解释了几个关键的实验观察结果:(1)该反应具有立体立体选择性,其中赤-二溴化物提供反式烯烃,而苏-二溴化物提供顺式烯烃,(2)该反应可进一步促进反应。富含电子的二有机碲化物,(3)在极性更大的溶剂中加速反应,(4)通过向带有溴取代基的碳中添加稳定碳阳离子的取代基来加速反应,(5)赤型二溴化物非常多比苏式二溴化物更具反应性。有人提出,维他命二溴化物形成溴离子的速度很慢,而且速度决定。形成溴离子后,快速清除“