A Sustainable and Catalyst-Free Direct Photochemical Route for the Conversion of Amines to Imines via C–N Coupling Reaction Under Ambient Conditions

Abstract

Amine to imine conversion via C–N coupling pathway is an important class of chemical transformation having tremendous importance in the synthesis of fine chemicals and pharmaceuticals. However, selective conversion of amines to imines requires harsh reaction conditions and/or metal-based catalysts. Here, we report a catalyst-free direct photochemical route for the 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 from amines to 1O2 with the formation of iminium cation intermediate. To our knowledge, this is the first report for an efficient, selective, and sustainable conversion of amines to imines under an ambient atmosphere without any additional catalysts/oxidants. © 2026 Wiley-VCH GmbH.