Electrochemical ammonium-cation-assisted pyridylation of inert N-heterocycles via dual-proton-coupled electron transfer

Cong Niu; Jianjing Yang; Kelu Yan; Jiafang Xie; Wei Jiang; Bingwen Li; Jiangwei Wen

doi:10.1016/j.isci.2022.104253

Electrochemical ammonium-cation-assisted pyridylation of inert N-heterocycles via dual-proton-coupled electron transfer

iScience. 2022 Apr 15;25(5):104253. doi: 10.1016/j.isci.2022.104253. eCollection 2022 May 20.

Authors

Cong Niu¹, Jianjing Yang¹, Kelu Yan¹, Jiafang Xie¹, Wei Jiang¹, Bingwen Li², Jiangwei Wen¹

Affiliations

¹ Institute of Medicine and Materials Applied Technologies, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, P. R. China.
² Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, P. R. China.

Abstract

A straightforward and practical strategy for pyridylation of inert N-heterocycles, enabled by ammonium cation and electrochemical, has been described. This protocol gives access to various N-fused heterocycles and bidentate nitrogen ligand compounds, through dual-proton-coupled electron transfer (PCET) and radical cross-coupling in the absence of exogenous metal and redox reagent. It features broad substrate scope, wide functional group tolerance, and easy gram-scale synthesis. Various experiments and density functional theory (DFT) calculation results show the mechanism of dual PCET followed by radical cross-coupling is the preferred pathway. Moreover, ammonium salt plays the dual role of protonation reagent and electrolyte in this conversion, and the resulting product 9-(pyridin-4-yl)acridine compound can be used for fluorescence recognition of Fe²⁺ and Pd²⁺ with high sensitivity.

Keywords: Catalysis; Electrochemistry; Transport phenomena.