Insight into Transmetalation Enables Cobalt-Catalyzed Suzuki-Miyaura Cross Coupling.
Insight into Transmetalation Enables Cobalt-Catalyzed Suzuki-Miyaura Cross Coupling.
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DOI：
10.1021/acscentsci.6b00283
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发表时间：
2016-12-28
影响因子：
18.2
通讯作者：
Chirik, Paul J.
中科院分区：
文献类型：
--
作者：
Neely, Jamie M.;Bezdek, Mate J.;Chirik, Paul J.
在组成交叉偶联催化循环的基本转变中，从亲核试剂到金属催化剂的易金属转化可能是最不被了解的。优化这一基本步骤，实现了第一个钴催化的铃木-宫仓交叉偶联的芳基三氟酸盐亲电体和杂芳基硼亲核试剂。这一发现的关键是制备和表征了一类新的四面体高自旋双(膦)吡啶钴(I)醇盐和芳氧基配合物(IPrPNP)Coor，并优化了它们与2-苯并呋喃基苯并呋喃(Pin)的反应性。具有小分子烷氧基的钴化合物，如R=甲基和乙基，在23℃下发生了快速的金属置换，但也被证明在动力学上对β-H的消除不稳定。二次醇盐如R=IPR或CH(Ph)Me平衡了稳定性和反应活性。转金属反应产物(IPrPNP)Co(2-苯并呋喃)的分离和结构表征表明，在该反应中钴(I)的高自旋态和低自旋态迅速相互转化，形成了一个平面的抗磁性钴(I)络合物。从这一基本步骤的研究中得到的见解指导了合适的反应条件的选择，使得第一批钴催化的C-C键在中性亲核试剂和三氟代芳基化合物之间形成C-C键，并提出了一个成功的转金属反应的模型。研究了中性硼试剂向高自旋钴(I)醇盐的转金属反应。对这种前所未有的反应性的了解使铃木钴催化的−宫浦交叉偶联的第一个例子得以发展。
Among the fundamental transformations that comprise a catalytic cycle for cross coupling, transmetalation from the nucleophile to the metal catalyst is perhaps the least understood. Optimizing this elementary step has enabled the first example of a cobalt-catalyzed Suzuki–Miyaura cross coupling between aryl triflate electrophiles and heteroaryl boron nucleophiles. Key to this discovery was the preparation and characterization of a new class of tetrahedral, high-spin bis(phosphino)pyridine cobalt(I) alkoxide and aryloxide complexes, (iPrPNP)CoOR, and optimizing their reactivity with 2-benzofuranylBPin (Pin = pinacolate). Cobalt compounds with small alkoxide substituents such as R = methyl and ethyl underwent swift transmetalation at 23 °C but also proved kinetically unstable toward β–H elimination. Secondary alkoxides such as R = iPr or CH(Ph)Me balanced stability and reactivity. Isolation and structural characterization of the product following transmetalation, (iPrPNP)Co(2-benzofuranyl), established a planar, diamagnetic cobalt(I) complex, demonstrating the high- and low-spin states of cobalt(I) rapidly interconvert during this reaction. The insights from the studies in this elementary step guided selection of appropriate reaction conditions to enable the first examples of cobalt-catalyzed C–C bond formation between neutral boron nucleophiles and aryl triflate electrophiles, and a model for the successful transmetalation reactivity is proposed. Transmetalation from neutral boron reagents to high spin cobalt(I) alkoxides was examined. Understanding this unprecendented reactivity enabled the development of the first example of cobalt-catalyzed Suzuki−Miyaura cross coupling.
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影响因子：
15
作者：
Daifuku SL;Kneebone JL;Snyder BE;Neidig ML
通讯作者：
Neidig ML
影响因子：
5.4
作者：
Corpet, Martin;Bai, Xian-Zhou;Gosmini, Corinne
通讯作者：
Gosmini, Corinne
影响因子：
4
作者：
Dunsford, Jay J.;Clark, Ewan R.;Ingleson, Michael J.
通讯作者：
Ingleson, Michael J.
影响因子：
4.3
作者：
Amatore, Christian;Le Duc, Gaetan;Jutand, Anny
通讯作者：
Jutand, Anny
影响因子：
4.3
作者：
Gonnard, Laurine;Guerinot, Amandine;Cossy, Janine
通讯作者：
Cossy, Janine