Ruthenium Catalyzed Additive‐Free N ‐Formylation of Amines with CO 2 and H 2 : Exploring Carbon Neutral Hydrogen Cycle

The N ‐formylation of amines using CO 2 hydrogenation, conducted under additive‐free conditions, represents a crucial methodology in organic synthesis. Herein, we demonstrated a highly efficient ruthenium pincer complex for the selective conversion of a wide array of amines into their corresponding formamides under additive‐free condition with a turnover number (TON) of 980,000 within a single‐batch. Controlled studies suggested the initial reduction of CO 2 to ammonium formate, followed by dehydration to generate formamide. NMR experiments revealed the potential intermediates and indicated the involvement of metal‐ligand cooperativity of catalyst during substrate activation. In addition, this methodology was examined to establish a carbon neutral hydrogen storage cycle by capitalizing on the reversible transformation of formamides.