Atroposelective Synthesis of Axially Chiral Styrenes via an Asymmetric C–H Functionalization Strategy
作者:Liang Jin、Qi-Jun Yao、Pei-Pei Xie、Ya Li、Bei-Bei Zhan、Ye-Qiang Han、Xin Hong、Bing-Feng Shi
DOI:10.1016/j.chempr.2019.12.011
日期:2020.2
Axially chiral styrenes, which exhibit a chiral axis between a substituted alkene and an aromatic ring, have been largely overlooked. The hurdle is the lower barriers to rotation compared with that of their biaryl counterparts, rendering their asymmetric synthesis more difficult. We report herein the highly atroposelective synthesis via a C−H functionalization strategy of axially chiral styrenes with an open-chained
在取代烯烃和芳族环之间显示手性轴的轴向手性苯乙烯已被大大忽略。与联芳基化合物相比,障碍是较低的旋转障碍,使其不对称合成更加困难。我们在此报告了通过轴向手性苯乙烯与开链烯烃的C H官能化策略进行的高度阻转选择性合成。通过使用L-焦谷氨酸作为廉价的手性配体,通过Pd(II)催化的CH链烯基化和炔基化反应可制得各种轴向手性苯乙烯,产率高(高达99%)和对映选择性(高达99%ee)。苯乙烯阻转异构体的有效应用通过二茂铁的Co(III)催化对映选择性CH酰胺化而得到,其中轴向手性苯乙烯型酸为手性配体。进行了实验和计算研究以阐明反应机理。基于DFT计算,还提供了确定对映选择性的CH键激活步骤的手性诱导模型。