Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
Department of Chemistry, University of Jyvaskyla, P.O. Box 35, 40114 Jyväskylä, Finland.
J Am Chem Soc. 2021 Jun 9;143(22):8375-8380. doi: 10.1021/jacs.1c01797. Epub 2021 May 25.
We report a remote functionalization strategy, which allows the -selective synthesis of silyl enol ethers of (hetero)aromatic and aliphatic ketones via Ni-catalyzed chain walking from a distant olefin site. The positional selectivity is controlled by the directionality of the chain walk and is independent of thermodynamic preferences of the resulting silyl enol ether. Our mechanistic data indicate that a Ni dimer is formed under these conditions, which serves as a catalyst resting state and, upon reaction with an alkyl bromide, is converted to [Ni-H] as an active chain-walking/functionalization catalyst, ultimately generating a stabilized η-bound Ni enolate as the key selectivity-controlling intermediate.
我们报告了一种远程功能化策略，该策略允许通过 Ni 催化的从远程烯烃位点的链行走来选择性地合成（杂）芳族和脂肪族酮的硅基烯醇醚。位置选择性受链行走的方向性控制，与所得硅基烯醇醚的热力学偏好无关。我们的机理数据表明，在这些条件下形成 Ni 二聚体，其作为催化剂的静止状态，并在与烷基溴反应时，转化为[Ni-H]作为活性链行走/功能化催化剂，最终生成稳定的η键合 Ni 烯醇盐作为关键的选择性控制中间体。
