OXIDATION‐DEFORMYLATION CASCADE CATALYZED BY A MONONUCLEAR COPPER COMPLEX

In this study, two copper complexes were synthesized using N3 (arising from two pyridines and one amide group) containing ligands N‐(2‐picolyl)picolinamide (L1H) and bis(2‐pyridylcarbonyl)amine (L2H), forming [(L1)CuII(OH2)(NO3)] (1) and [(L2)CuII(OH2)2](NO3) (2). The reaction of complex 1 with hydrogen peroxide in alcoholic solvents yielded a formate‐bound complex. Studies with isotopically labeled 13C ethanol indicated that formate originates from the C1 of ethanol after C‐C bond cleavage. Complex 1 was found to catalytically convert primary alcohols into formic acid probably following a two‐step process: (i) alcohol oxidation to aldehyde and (ii) aldehyde deformylation. Further experiments with 2‐phenylpropionaldehyde (2‐PPA) confirm the ability of complex 1 to catalyze aldehyde deformylation. Both steps of the reaction are associated with significant kinetic deuterium isotope effects (KDIE), suggesting that hydrogen atom abstractions (HAA) occur during the rate‐determining steps of both conversions. Overall, this system proposes a clean catalytic process for alcohol‐to‐formic acid conversion, operating under mild conditions, and offering potential synthetic applications.