Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst
Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst
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DOI：
10.1021/jacs.0c11601
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发表时间：
2021-02-08
影响因子：
15
通讯作者：
Miller, Alexander J. M.
中科院分区：
文献类型：
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作者：
Camp, Andrew M.;Kita, Matthew R.;Miller, Alexander J. M.
双键的催化转位有望成为一种理想的路线，以烯烃的价值作为香料，商品化学品和药物;然而，选择性地获得特定的异构体是一个挑战，通常需要独立开发不同的催化剂用于不同的产品。在这项工作中，一个单一的阳离子响应铱催化剂选择性地产生两种不同的内部烯烃异构体。在不存在盐的情况下，1-丁烯衍生物的单一位置异构化以特殊的区域选择性和立体选择性取代2-烯烃。相同的催化剂，在Na+的存在下，介导两个位置异构化，以产生3-烯烃。基于氮杂-18-冠-6醚的新型铱钳形冠醚催化剂的合成证明有助于实现阳离子控制的选择性。实验和计算研究指导了一个机制模型的发展，该模型解释了观察到的各种官能化1-丁烯的选择性，提供了深入了解基于非共价修饰的催化剂开发策略。
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.