N-Formylation of Amines with CO₂ and H₂ by Using NHC-Iridium Coordination Assemblies as Solid Molecular Catalysts

One of the NHC-iridium coordination assemblies containing 1,5-cyclooctadiene (COD) and iodide ion has been demonstrated as robust, efficient, recyclable solid molecular catalyst for N-formylation of diverse primary and secondary amines with CO₂ and H₂ under mild reaction conditions. Remarkably, in the case of N,N-dimethylformamide production, even at 0.1 mol % catalyst loading under solvent-free conditions, the solid catalyst can be readily recovered by simply filtration and reused more than 10 runs without noticeable loss of activity.