中国科学院游书力团队揭示了铱催化Z式保留不对称烯丙基取代反应机制。 相关研究成果发表在2021年1月22日出版的《科学》。

由于其相对的热力学不稳定性，Z-烯烃是具有挑战性的合成目标。过渡金属催化的不对称烯丙基取代反应是众所周知的用于安装立体中心附近的支链或E-线性烯烃。然而，用于合成光学活性Z-烯烃产品的类似反应很少。

该文中，研究人员报告了一种铱催化的不对称烯丙基取代反应策略，保留Z-烯烃的几何形状，同时建立一个相邻的四元立体中心。观察到瞬时反π-烯丙基铱中间体的形成及其在异构化为热力学上更稳定的顺π-烯丙基铱中间体之前被外部亲核试剂捕获。

这些结果为制备手性Z-烯烃化合物提供了一种很有前景的方法。

附：英文原文

Title: Iridium-catalyzed Z-retentive asymmetric allylic substitution reactions

Author: Ru Jiang, Lu Ding, Chao Zheng, Shu-Li You

Issue&Volume: 2021/01/22

Abstract: Z-Olefins are challenging synthetic targets owing to their relative thermodynamic instability. Transition metal–catalyzed asymmetric allylic substitution reactions are well known for installing stereocenters adjacent to branched or E-linear olefins. However, analogous reactions for the synthesis of optically active Z-olefin products are rare. Here we report iridium-catalyzed asymmetric allylic substitution reactions that retain Z-olefin geometries while establishing an adjacent quaternary stereocenter. The formation of transient anti-π-allyl-iridium intermediates and their capture by external nucleophiles before isomerization to the thermodynamically more stable syn-π-allyl-iridium counterparts have been observed. These results provide a promising method for preparing chiral Z-olefinic compounds.

DOI: 10.1126/science.abd6095

Source: https://science.sciencemag.org/content/371/6527/380