Volume 247, 2023

Mechanistic studies of Ni-catalyzed electrochemical homo-coupling reactions of aryl halides

Abstract

Ni-catalyzed electrochemical arylation is an attractive, emerging approach for molecular construction as it uses air-stable Ni catalysts and efficiently proceeds at room temperature. However, the homo-coupling of aryl halide substrates is one of the major side reactions. Herein, extensive experimental and computational studies were conducted to examine the mechanism of Ni-catalyzed electrochemical homo-coupling of aryl halides. The results indicate that an unstable NiII(Ar)Br intermediate formed through oxidative addition of the cathodically generated NiI species with aryl bromide and a consecutive chemical reduction step. For electron-rich aryl halides, homo-coupling reaction efficiency is limited by the oxidative addition step, which can be improved by negatively shifting the redox potential of the Ni-catalyst. DFT computational studies suggest a NiIII(Ar)Br2/NiII(Ar)Br ligand exchange pathway for the formation of a high-valent NiIII(Ar)2Br intermediate for reductive elimination and production of the biaryl product. This work reveals the reaction mechanism of Ni-catalyzed electrochemical homo-coupling of aryl halides, which may provide valuable information for developing cross-coupling reactions with high selectivity.

Graphical abstract: Mechanistic studies of Ni-catalyzed electrochemical homo-coupling reactions of aryl halides

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Supplementary files

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Article information

Article type
Paper
Submitted
17 Mar 2023
Accepted
23 May 2023
First published
23 May 2023

Faraday Discuss., 2023,247, 136-146

Author version available

Mechanistic studies of Ni-catalyzed electrochemical homo-coupling reactions of aryl halides

J. Luo, M. T. Davenport, A. Carter, D. H. Ess and T. L. Liu, Faraday Discuss., 2023, 247, 136 DOI: 10.1039/D3FD00069A

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