Controlling Ni redox states by dynamic ligand exchange for electroreductive Csp3-Csp2 coupling.
Controlling Ni redox states by dynamic ligand exchange for electroreductive Csp3-Csp2 coupling.
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电还原Csp3-Csp2偶联的动态配体交换控制Ni氧化还原态。
DOI：
10.1126/science.abo0039
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发表时间：
2022-04-22
期刊：
影响因子：
56.9
通讯作者：
Sevov, Christo S.
中科院分区：
文献类型：
--
作者：
Hamby, Taylor B.;LaLama, Matthew J.;Sevov, Christo S.
芳基亲电试剂和烷基亲电试剂的交叉亲电试剂偶联（XEC）反应是有吸引力的，但限于特定的底物类别。在这里，我们报告电还原XEC以前不兼容的亲电试剂，包括叔烷基溴，芳基氯，和芳基/乙烯基三氟甲磺酸酯。反应依赖于通过1 e-过程选择性地与烷基溴反应的电化学活性络合物和通过2 e-过程选择性地与芳基亲电试剂反应的电化学非活性Ni 0（膦）络合物的合并。Ni 0（膦）中间体对该战略至关重要，但往往具有挑战性。我们发现了一个以前未知的途径，电化学产生这些关键的复合物在温和的电位通过一系列精心设计的配体交换反应。温和的方法适用于一系列底物的烷基化，包括天然产物和药物。碳-碳键形成的交叉偶联催化的发展彻底改变了药物合成。尽管如此，原始反应的一个缺点是需要提前激活其中一个偶联配偶体。最近，化学家们专注于两种卤代烃的直接偶联，这是有效的，但提出了选择性的挑战。Hamby等人报道了一种用于烷基-芳基偶联的镍催化剂，其依赖于与电化学协同的配体交换，以连续地与每个配偶体反应，从而避免烷基-烷基、芳基-芳基或异构化的副产物。-JSY
Cross-electrophile coupling (XEC) reactions of aryl and alkyl electrophiles are appealing but limited to specific substrate classes. Here, we report electroreductive XEC of previously incompatible electrophiles including tertiary alkyl bromides, aryl chlorides, and aryl/vinyl triflates. Reactions rely on the merger of an electrochemically active complex that selectively reacts with alkyl bromides through 1e– processes and an electrochemically inactive Ni0(phosphine) complex that selectively reacts with aryl electrophiles through 2e– processes. Accessing Ni0(phosphine) intermediates is critical to the strategy but is often challenging. We uncover a previously unknown pathway for electrochemically generating these key complexes at mild potentials through a choreographed series of ligand-exchange reactions. The mild methodology is applied to the alkylation of a range of substrates including natural products and pharmaceuticals. The development of cross-coupling catalysis for carbon-carbon bond formation revolutionized pharmaceutical synthesis. Nonetheless, one drawback of the original reactions is the need to activate one of the coupling partners ahead of time. Recently, chemists have focused on direct coupling of two halocarbons, which is efficient but poses a selectivity challenge. Hamby et al. report a nickel catalyst for alkyl-aryl coupling that relies on ligand exchanges in concert with electrochemistry to react with each partner consecutively and thereby avoid alkyl-alkyl, aryl-aryl, or isomerized by-products. —JSY
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影响因子：
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