Visible light promoted PANI@Au:CuO catalyzed sequential amination, azidation and annulation for the preparation of 2-arylbenzimidazoles

Abstract

Supramolecular assemblies of pentacenequinone derivative 4 act as reactors, reducing agents and shape directing agents for the preparation of PANI@Au:CuO nanocomposites (NCS). The as-prepared PANI@Au:CuO NCS serve as recyclable photocatalysts to construct 2-arylbenzimidazole derivatives under mild conditions through sequential amination, azidation and annulation reactions (visible light irradiation, room temperature and aerial conditions). The present protocol emphasizes the role of assemblies of the pentacenequinone derivative as visible light harvesting materials as well as oxidants in multiple C–N bond formation reactions. To our delight, the reaction also worked well under natural sunlight. The mechanistic studies supported the in situ generation of H2O2 during the reaction. Further, a portable paper based “dip catalyst” has been developed for carrying out sequential amination, azidation and annulation reactions.