Visible‐Light‐Driven Selective Oxidative Coupling of Amines to Imines by Bismuth‐Rich Bismuth Oxybromide in Water

Photocatalytic selective oxidative coupling of amines is a promising method for imine synthesis. Bismuth‐rich bismuth oxybromide photocatalysts have been found to exhibit improved conversion and selectivity for the visible‐light‐driven selective oxidative coupling of amines to imines in water. Benzylamines with either electron‐withdrawing or electron‐donating groups undergo good conversion (94–99 %) and excellent selectivity (93–98 %) to the corresponding imines. The average apparent quantum efficiency at 455 nm is 57.4 %. Active species trapping experiments, isotope experiments, and in situ infrared spectroscopy reveal that water both serves as solvent and participates in the coupling reaction as a reactant. This work provides a green and environmentally friendly method for the efficient synthesis of imines with bismuth‐rich bismuth oxyhalides and reveals water is involved in the oxidative coupling mechanism of benzylamines.