Oxygen Vacancy Boosts Nitrogen-Centered Radical Coupling\nInitiated\nby Primary Amine Electrooxidation

Synthesis of nitrogen-centered radicals (NCRs) for radical\ncoupling\nreactions is a powerful and versatile tool in the arsenal of organic\nsynthetic chemistry. However, there are few reports on the direct\nsynthesis of NCRs based on aqueous electrocatalysis. Herein, we present\na new electrochemical primary amine oxidation reaction (ePAOR) system\nwith R<sub>1</sub>R<sub>2</sub>-CH-NH<sub>2</sub> as the substrate\nfor synthesizing NCRs and N–N coupling products. However, ePAOR\non the model catalyst (NiO) suffers from low N–N coupling selectivity\ndue to the weak adsorption energy of imine (R<sub>1</sub>R<sub>2</sub>-CNH) intermediates. Guided by theoretical calculations,\nthe 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\nradical coupling initiated by the ePAOR on oxygen vacancy-rich NiO\n(V<sub>O</sub>-NiO), and the effective utilization rate of NCRs was\nincreased from 36 to 75%. This approach is compatible with a wide\nrange of primary amines and can be applied to N–N cross-coupling\nsystems as well.