Ru@PsIL‐Catalyzed Synthesis of N‐Formamides and Benzimidazole by using Carbon Dioxide and Dimethylamine Borane

This work reports the synthesis and characterization of ruthenium nanoparticles (Ru NPs) supported on polymeric ionic liquids (PILs). This catalyst shows high catalytic activity towards the N‐formylation of amines and synthesis of benzimidazoles from 1,2‐diamines and carbon dioxide (CO₂) by reductive dehydrogenation of dimethylamine borane. This methodology shows excellent functional group tolerance with broad substrate scope towards the synthesis of N‐formamides and benzimidazoles. Interestingly, this protocol also provides the tandem reduction of 2‐nitroamines and CO₂ to synthesize benzimidazoles. It was proposed that the ionic liquid phase of the polymer plays pivotal roles such as assisting the stabilization of nanoparticles electrostatically, providing an ionic environment, and controlling the easy access of the substrates/reagents to the active sites. The developed methodology utilizes CO₂ as a C₁ source and water/ethanol as a green solvent system. Additionally, the catalyst was found to be recyclable in nature and shows five consecutive recycling runs without significant loss in its activity.