A Catalyst‐free direct photochemical route for the conversion of amines to imines via C–N coupling reaction under ambient conditions

Amine to imine conversion via C–N coupling pathway is an important class of chemical transformation that find significant importance during the synthesis of fine chemicals and pharmaceuticals. However, selective conversion of amines to imines requires harsh reaction conditions and/or metal-based catalysts. Herein, we report a catalyst-free direct photochemical route for the efficient and selective conversion of amines to imines under ambient conditions. The present approach utilizes in situ generated singlet oxygen (1O2) as an oxidizing agent from the solvent-3O2 charge transfer transition in neat solvent for the conversion of amines to imines under 370–440 nm light irradiation. This conversion proceeds with the generation of ammonia and hydrogen peroxide as byproducts. Detailed mechanistic investigations revealed single electron transfer (SET) from amines to 1O2 with the formation of iminium cation intermediate. To our knowledge, this is the first report for the efficient, selective, and sustainable conversion of amines to imines under an ambient atmosphere without any additional catalysts/oxidants.