Aerobic Oxidation of Benzyl Amines to Benzyl Imines Catalyzed by Metal-Organic Framework Solids

N-Hydroxyphthalimide (NHPI) incorporated on a Fe-III-based metal-organic framework [NHPI/Fe(BTC), BTC: 1,3,5-benzenetricarboxylate)] is used as a heterogeneous catalyst for the aerobic oxidation of benzylamine and its derivatives to their corresponding benzyl imines under neat conditions with molecular oxygen as only oxidant at 100 degrees C. The catalytic activity of NHPI/Fe(BTC) compares favorably with other heterogeneous catalysts (supported gold nanoparticles) in terms of percentage conversion and selectivity. The reaction appears general in scope and various benzyl amines including heterocyclic amines are also oxidized to the corresponding imines under the present catalytic system. Cross condensation of benzylamine with aniline forms N-phenylimine in moderate yields. These findings lead to a simple synthetic procedure using commercially available raw materials and eliminate the use of conventional organic solvents.