Copper-Carbon Homolysis Competes with Reductive Elimination in Well-Defined Copper(III) Complexes

Wenhao Yan, Samantha Carter, Chi Tien Hsieh, Jeanette A. Krause, Mu Jeng Cheng, Shiyu Zhang, Wei Liu

研究成果: Article同行評審

7 引文 斯高帕斯(Scopus)

摘要

Despite the recent advancements of Cu catalysis for the cross-coupling of alkyl electrophiles and the frequently proposed involvement of alkyl-Cu(III) complexes in such reactions, little is known about the reactivity of these high-valent complexes. Specifically, although the reversible interconversion between an alkyl-CuIII complex and an alkyl radical/CuII pair has been frequently proposed in Cu catalysis, direct observation of such steps in well-defined CuIII complexes remains elusive. In this study, we report the synthesis and investigation of alkyl-CuIII complexes, which exclusively undergo a Cu-C homolysis pathway to generate alkyl radicals and CuII species. Kinetic studies suggest a bond dissociation energy of 28.6 kcal/mol for the CuIII-C bonds. Moreover, these four-coordinate complexes could be converted to a solvated alkyl-CuIII-(CF3)2, which undergoes highly efficient C-CF3 bond-forming reductive elimination even at low temperatures (−4 °C). These results provide strong support for the reversible recombination of alkyl radicals with CuII to form alkyl-CuIII species, an elusive step that has been proposed in Cu-catalyzed mechanisms. Furthermore, our work has demonstrated that the reactivity of CuIII complexes could be significantly influenced by subtle changes in the coordination environment. Lastly, the observation of the highly reactive neutral alkyl-CuIII-(CF3)2 species (or with weakly bound solvent molecules) suggests they might be the true intermediates in many Cu-catalyzed trifluoromethylation reactions.

原文English
頁(從 - 到)26152-26159
頁數8
期刊Journal of the American Chemical Society
145
發行號48
DOIs
出版狀態Published - 2023 12月 6

All Science Journal Classification (ASJC) codes

  • 催化
  • 一般化學
  • 生物化學
  • 膠體和表面化學

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