Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
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DOI：
10.1021/jacs.0c03184
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发表时间：
2020-06-24
影响因子：
15
通讯作者：
Morandi, Bill
中科院分区：
文献类型：
--
作者：
Bhawal, Benjamin N.;Reisenbauer, Julia C.;Morandi, Bill
可逆催化反应在热力学控制下进行，因此，建立选择性催化体系提出了相当大的挑战。在此，我们报告了一种可逆转移氢氰化方案，该方案对热力学不太有利的支化异构体表现出高选择性。选择性是通过在不存在助催化路易斯酸的情况下利用苄基位置上 C-CN 氧化加成和还原消除的较低势垒来实现的。通过设计新型HCN供体，实现了实用的、支链选择性、无HCN转移氢氰化。支链和直链腈异构体混合物的合成有用拆分也被证明强调了可逆和选择性转移反应的价值。在更广泛的背景下，这项工作证明了可逆转移反应可以实现高动力学选择性，从而为其合成应用开辟了新的视野。
Reversible catalytic reactions operate under thermodynamic control, and thus, establishing a selective catalytic system poses a considerable challenge. Herein, we report a reversible transfer hydrocyanation protocol that exhibits high selectivity for the thermodynamically less favorable branched isomer. Selectivity is achieved by exploiting the lower barrier for C-CN oxidative addition and reductive elimination at benzylic positions in the absence of a cocatalytic Lewis acid. Through the design of a novel type of HCN donor, a practical, branched-selective, HCN-free transfer hydrocyanation was realized. The synthetically useful resolution of a mixture of branched and linear nitrile isomers was also demonstrated to underline the value of reversible and selective transfer reactions. In a broader context, this work demonstrates that high kinetic selectivity can be achieved in reversible transfer reactions, thus opening new horizons for their synthetic applications.