Bess Elizabeth N, Guptill David M, Davies Huw M L, Sigman Matthew S
Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , UT 84112 , USA . Email:
Department of Chemistry , Emory University , 1515 Dickey Drive , Atlanta , GA 30322 , USA . Email:
Chem Sci. 2015 May 1;6(5):3057-3062. doi: 10.1039/c5sc00357a. Epub 2015 Mar 18.
Achieving selective C-H functionalization is a significant challenge that requires discrimination between many similar C-H bonds. Yet, reaction systems employing Rh(DOSP) and Rh(BPCP) were recently demonstrated to afford high levels of selectivity in the C-H insertion of carbenes into toluene-derived substrates. Herein, we explore the origin of this selectivity through a systematic analysis of substrate and reagent features that alter levels of selectivity from 20 : 1 to 1 : 610 for secondary (or tertiary)-to-primary benzylic C-H functionalization of toluene derivatives. Describing this variation using infrared vibrations and point charges, we have developed a mathematical model from which are identified features of the systems that determine levels of site-selectivity and are applied as predictive factors to describe the selectivity behavior of new substrate/reagent combinations.
实现选择性C-H官能化是一项重大挑战，需要区分许多相似的C-H键。然而，最近证明使用Rh(DOSP)和Rh(BPCP)的反应体系在卡宾插入甲苯衍生底物的C-H反应中具有高度的选择性。在此，我们通过系统分析底物和试剂特征来探究这种选择性的来源，这些特征将甲苯衍生物仲（或叔）-伯苄基C-H官能化的选择性水平从20∶1改变至1∶610。利用红外振动和点电荷描述这种变化，我们开发了一个数学模型，从中识别出决定位点选择性水平的体系特征，并将其用作预测因子来描述新底物/试剂组合的选择性行为。
