Nickel–Carbon Bond Oxygenation with Green Oxidants via High-Valent Nickel Species
Nickel–Carbon Bond Oxygenation with Green Oxidants via High-Valent Nickel Species
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通过高价镍物质与绿色氧化剂进行镍-碳键氧化
DOI：
10.1021/jacs.3c01012
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发表时间：
2023
影响因子：
15
通讯作者：
Mirica, Liviu M.
中科院分区：
文献类型：
--
作者：
Hu, Chi-Herng;Kim, Seoung-Tae;Baik, Mu-Hyun;Mirica, Liviu M.
本文描述了Ni II络合物（tBuMe 2 tacn）Ni II（cycloneophyl）（tBuMe 2 tacn = 1-叔丁基-4，7-二甲基-1，4，7-三氮杂环壬烷，cycloneophyl =-CH 2 CMe 2-o-C6 H 4-）的合成及其与分子氧和过氧化物的反应性。的newtBuMe 2 tacn配体的设计，以提高氧化诱导的键形成反应性的高价镍中间体。通过选择合适的溶剂和反应条件，实现了Csp 2-O与Csp 2-Csp 3键形成的可调化学选择性。重要的是，氢过氧化枯烯和间氯过苯甲酸的使用表明在与（tBuMe 2 tacn）NiII（cycloneophyl）反应时异裂O-O键断裂。使用同位素标记的H2 O2的机制研究支持通过内球机制和随后的还原消除形成Csp 2-O键的高价Ni-氧物种的产生。非常快的Csp 2-O键形成反应的动力学研究揭示了一级依赖于（tBuMe 2 tacn）镍II（cycloneophyl）和H2 O2，因此，整体二级反应。Eyring分析进一步表明，H_2O_2对Ni Ⅱ配合物的氧化是反应的速率控制步骤，配位溶剂的存在可以调节反应的速率.此外，计算研究完全支持从实验结果中得出的结论。总的来说，这项研究首次揭示了在Ni中心控制氧化诱导的C-C与C-O键形成反应的能力。重要的是，所描述的系统将已知的Ni的有机金属反应性与类似于加氧酶和过氧化物酶的仿生氧化转化相结合，并且涉及高价金属-氧中间体，这是一种新颖的方法，应该导致前所未有的氧化催化转化。
Described herein is the synthesis of the NiIIcomplex (tBuMe2tacn)NiII(cycloneophyl) (tBuMe2tacn = 1-tert-butyl-4,7-dimethyl-1,4,7-triazacyclononane, cycloneophyl = −CH2CMe2-o-C6H4−) and its reactivity with dioxygen and peroxides. The newtBuMe2tacn ligand is designed to enhance the oxidatively induced bond-forming reactivity of high-valent Ni intermediates. Tunable chemoselectivity for Csp2–O vs Csp2–Csp3bond formation was achieved by selecting the appropriate solvent and reaction conditions. Importantly, the use of cumene hydroperoxide andmeta-chloroperbenzoic acid suggests a heterolytic O–O bond cleavage upon reaction with (tBuMe2tacn)NiII(cycloneophyl). Mechanistic studies using isotopically labeled H2O2support the generation of a high-valent Ni-oxygen species via an inner-sphere mechanism and subsequent reductive elimination to form the Csp2–O bond. Kinetic studies of the exceptionally fast Csp2–O bond-forming reaction reveal a first-order dependence on both (tBuMe2tacn)NiII(cycloneophyl) and H2O2, and thus an overall second-order reaction. Eyring analysis further suggests that the oxidation of the NiIIcomplex by H2O2is the rate-determining step, which can be modulated by the presence of coordinating solvents. Moreover, computational studies fully support the conclusions drawn from experimental results. Overall, this study reveals for the first time the ability to control the oxidatively induced C–C vs C–O bond formation reactions at a Ni center. Importantly, the described system merges the known organometallic reactivity of Ni with the biomimetic oxidative transformations resembling oxygenases and peroxidases, and involving high-valent metal-oxygen intermediates, which is a novel approach that should lead to unprecedented oxidative catalytic transformations.