近日，中国科学院上海有机化学研究所沈其龙团队研究了Ullmann型偶联反应中铜的氧化还原行为的解码。2025年9月22日，《自然》杂志发表了这一成果。

铜催化芳基卤化物的功能化是形成碳-碳和碳杂原子键的首选方法之一。然而，铜在催化循环中的氧化还原行为仍然是一个很有争议的话题。研究组报道了一种定义明确的Cu(I)配合物与电子贫乏的芳基碘化物反应的实验和理论机理研究，这种反应导致形成可分离的Cu(III)芳基络合物，随后还原消除形成C(sp²)CF₃键。

研究组的综合实验和理论结果表明，该过程是通过Cu(I)/Cu(III)/Cu(II)/Cu(III)/Cu(I)的氧化还原顺序进行的。此外，研究组设法通过温度控制中断这一序列，并通过各种光谱方法捕获铜的反应性，促进深入的机理分析。这些发现揭示了铜的复杂行为，挑战了铜(I)与碘化芳基反应的传统机理，为铜催化偶联反应的机理方面提供了新的视角。

附：英文原文

Title: Decoding the redox behaviour of copper in Ullmann-type coupling reactions

Author: Luo, Yongrui, Li, Yuli, Wu, Botao, Wang, Guangyu, Wu, Jian, Zhang, Sheng-Ye, Houk, K. N., Shen, Qilong

Issue&Volume: 2025-09-22

Abstract: The copper-catalysed functionalization of aryl halides is one of the most preferred methods for the formation of carbon-carbon and carbon-heteroatom bonds.1 Yet, the redox behaviour of the copper species in the catalytic cycle remains elusive and a subject of considerable debate.2 We report experimental and theoretical mechanistic investigations into the reaction of a well-defined Cu(I) complex with an electron-poor aryl iodide, which leads to the formation of an isolable Cu(III)aryl complex, that subsequently reductively eliminates to forge a C(sp2)CF3 bond. Our integrated experimental and theoretical findings indicate that the process proceeds through a redox sequence of Cu(I)/Cu(III)/Cu(II)/Cu(III)/Cu(I). Additionally, we managed to interrupt this sequence by temperature control and captured the reactivity of the copper species through various spectroscopic methods, facilitating in-depth mechanistic analysis. These findings shed light on the intricate behaviour of copper species and challenge the traditional mechanistic proposal for the reaction of Cu(I) with aryl iodide, thus providing fresh perspectives into the mechanistic aspect of the copper-catalysed coupling reactions.

DOI: 10.1038/s41586-025-09627-2

Source: https://www.nature.com/articles/s41586-025-09627-2