Photoreductive N–N Homocoupling Catalyzed by a Superphotoreductant

Azines are valuable synthons or target molecules in organic synthesis. In this work, we report that CBZ6 could work as a photoreductive catalyst for the N–N homocoupling of oximes in high efficiency. This therefore enabled convenient access to a large variety of azines from the corresponding aryl and alkyl ketones, as well as aryl aldehydes in up to 99% yield. 2,4-Dinitrophenoxyl was used as the recyclable auxiliary and the CBZ6 photocatalyst could also be recycled. These together with the low catalyst loading (2 mol % of CBZ6), the short reaction time (4 h), and the nontoxic DMSO solvent make the current process a sustainable and practical alternative to the classic methods.