Three-Coordinate Copper(II) Alkynyl Complex in C-C Bond Formation: The Sesquicentennial of the Glaser Coupling
Three-Coordinate Copper(II) Alkynyl Complex in C-C Bond Formation: The Sesquicentennial of the Glaser Coupling
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DOI：
10.1021/jacs.0c07137
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发表时间：
2020-10-28
影响因子：
15
通讯作者：
Warren, Timothy H.
中科院分区：
文献类型：
--
作者：
Bakhoda, Abolghasem;Okoromoba, Otome E.;Warren, Timothy H.
铜（II）炔基物被认为是许多cu催化的C-C偶联反应的关键中间体，在β -二酮酸配体的支持下，三配位铜（II）炔基[Cu-II] -c CAr （Ar = 2,6- cl2c6h3）在炔H-C CAr与铜（II）叔丁醇配合物[Cu-II] -(OBu)- bu -i反应时形成。在溶液中，这种[Cu-II]-C CAr清晰地转变为激光偶联产物At-C -C CAr和[Cu-I]（溶剂）。在[Cu-II]- c CAr中加入亲核试剂R' C-C - li （R' =芳基，硅基）和Ph-Li，得到相应的C-sp-C-sp和C-sp-C-sp2偶联产物RC C-C CAr和Ph-C CAr，并分别生成[Cu-I]（溶剂）和{[Cu-I]- c CAr}（-）。在密度泛函理论（DFT）计算的支持下，氧化还原歧化形成[Cu-III](C CAr)(R)物质，可还原消除R-C CAr产物。[Cu-II]-C CAr也捕获三基自由基Ph3C中心点，生成Ph3C-C CAr。自由基捕获是铜催化苯基底物R- h与炔烃H-C CR′（R′（杂基）芳基，硅基）形成C-sp-C-sp3键的关键步骤，通过自由基接力以‘BuOO’ bu为氧化剂提供C-sp-C-sp3偶联产物R- c CR。
Copper(II) alkynyl species are proposed as key intermediates in numerous Cu-catalyzed C-C coupling reactions Supported by a beta-diketiminate ligand, the three-coordinate copper(II) alkynyl [Cu-II] -C CAr (Ar = 2,6-Cl2C6H3) forms upon reaction of the alkyne H-C CAr with the copper(II) tertbutoxide complex [Cu-II] -(OBu)-Bu-i. In solution, this [Cu-II]-C CAr species cleanly transforms to the Glaser coupling product At-C C-C CAr and [Cu-I](solvent). Addition of nudeophiles R'C C-Li (R' = aryl, silyl) and Ph-Li to [Cu-II]-C CAr affords the corresponding C-sp-C-sp and C-sp-C-sp2 coupled products RC C-C CAr and Ph-C CAr with concomitant generation of [Cu-I](solvent) and {[Cu-I]-C CAr}(-), respectively. Supported by density functional theory (DFT) calculations, redox disproportionation forms [Cu-III](C CAr)(R) species that reductively eliminate R-C CAr products. [Cu-II]-C CAr also captures the trityl radical Ph3C center dot to give Ph3C-C CAr. Radical capture represents the key C-sp-C-sp3 bond-forming step in the copper-catalyzed C-H functionalization of benzylic substrates R-H with alkynes H-C CR' (R' (hetero)aryl, silyl) that provide C-sp-C-sp3 coupled products R-C CR via radical relay with 'BuOO'Bu as oxidant.