美国北卡罗来纳大学教堂山分校Alexander J. M. Miller研究团队揭示了单阳离子反应型铱烯烃异构化催化剂的双键位置选择策略。相关研究成果于2021年2月8日发表在国际顶尖学术期刊《美国化学会杂志》。

双键的催化转移有望成为制备有价值的烯烃（如香料、商品化学品和药品）的理想途径；然而，选择性地获得特定异构体是一个挑战，通常需要为不同的产品独立开发不同的催化剂。

在该研究中，一个单一的阳离子反应型铱催化剂选择性地产生两种不同的内部烯烃异构体。在没有盐的情况下，1-丁烯衍生物的单位置异构化可以得到具有特殊区域选择性和立体选择性的2-烯烃。同一催化剂在Na+存在下，介导两个位置异构化反应生成3-烯烃。

基于aza-18-冠-6醚的新型铱钳形冠醚催化剂的合成证明了实现阳离子控制选择性的重要性。实验和计算研究指导了一个机理模型的发展，该模型解释了观察到的各种功能化1-丁烯的选择性，为基于非共价修饰的催化剂开发策略提供了见解。

附：英文原文

Title: Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst

Author: Andrew M. Camp, Matthew R. Kita, P. Thomas Blackburn, Henry M. Dodge, Chun-Hsing Chen, Alexander J. M. Miller

Issue&Volume: February 8, 2021

Abstract: The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on noncovalent modifications.

DOI: 10.1021/jacs.0c11601

Source: https://pubs.acs.org/doi/10.1021/jacs.0c11601