Controlled Evolution of the Cope Rearrangement: Transition from Concerted to Interrupted and Aborted Pericyclic Reactions Regulated by a Switch Built from an Intramolecular Frustrated Lewis Pair
Controlled Evolution of the Cope Rearrangement: Transition from Concerted to Interrupted and Aborted Pericyclic Reactions Regulated by a Switch Built from an Intramolecular Frustrated Lewis Pair
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Cope重排的受控演化：由分子内受阻路易斯对构建的开关调节从协同反应到中断和中止的周环反应的转变
DOI：
10.1021/acs.joc.9b02633
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Alabugin, Igor V.
中科院分区：
文献类型：
--
作者：
Vidhani, Dinesh V.;Alabugin, Igor V.
我们展示了如何正确放置的受体和供体基团之间的协同作用，允许合理的设计中断和中止周环反应，使用的科普重排作为一个模型过程。当置于1，5-己二烯的C2和C5碳上时，由两个互补基团组成的受抑刘易斯对确保C-C键的形成通过C1-C6键的形成由电子密度从C5处的供体流入C2处的受体而得到帮助。如果在接受基团的电子过剩是强烈稳定的取代基的电子性质，周环过渡态可以成为一个能量最小值，导致开关从协调σ迁移到其中断或中断的版本。根据受体在C5和供体基团在C2的电子性质，从协调到中止的途径的可能性范围是可访问的，包括在不存在金属催化剂的情况下中止的科普重排的第一个例子。此外，两性离子策略稳定了通常不利的船TS，其可以潜在地演变成很少可获得的双环己烷产物。
We show how synergy between properly placed acceptor and donor groups allows rational design of interrupted and aborted pericyclic reactions, using the Cope rearrangement as a model process. When placed at C2 and C5 carbons of 1,5-hexadienes, a frustrated Lewis pair made of two complementary groups assures that the C–C bond formation is assisted by the flow of electron density from a donor at C5 into an acceptor at C2 through the formation of the C1–C6 bond. If the electron excess at the accepting group is strongly stabilized by the electronic nature of substituents, the pericyclic transition state can become an energy minimum, leading to a switch from a concerted sigmatropic shift to its aborted or interrupted versions. Depending on the electronic nature of acceptors at C5 and the donor groups at C2, a range of possibilities from concerted to aborted pathways is accessible, including the first example of an aborted Cope rearrangement in the absence of a metal catalyst. Furthermore, the zwitter-ionic strategy stabilizes the usually unfavorable boat TS that can potentially evolve into rarely accessible bicyclohexane products.