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Oxygen Vacancy Boosts Nitrogen-Centered Radical Coupling Initiated by Primary Amine Electrooxidation

MetadataDetails
Publication Date2024-11-22
JournalJournal of the American Chemical Society
AuthorsMengwei Han, Yongxiang Luo, Leitao Xu, Wei Chen, Chengmei Li
InstitutionsNational Synchrotron Radiation Research Center, Hunan University
Citations17

Synthesis of nitrogen-centered radicals (NCRs) for radical coupling reactions is a powerful and versatile tool in the arsenal of organic synthetic chemistry. However, there are few reports on the direct synthesis of NCRs based on aqueous electrocatalysis. Herein, we present a new electrochemical primary amine oxidation reaction (ePAOR) system with R<sub>1</sub>R<sub>2</sub>-CH-NH<sub>2</sub> as the substrate for synthesizing NCRs and N-N coupling products. However, ePAOR on the model catalyst (NiO) suffers from low N-N coupling selectivity due to the weak adsorption energy of imine (R<sub>1</sub>R<sub>2</sub>-C═NH) intermediates. Guided by theoretical calculations, the oxygen vacancy gives NiO a strong adsorption capacity of R<sub>1</sub>R<sub>2</sub>-C═NH so that it boosts nitrogen-centered radical coupling initiated by the ePAOR on oxygen vacancy-rich NiO (V<sub>O</sub>-NiO), and the effective utilization rate of NCRs was increased from 36 to 75%. This approach is compatible with a wide range of primary amines and can be applied to N-N cross-coupling systems as well.