Aerobic oxidation of alkyl aromatics to ketones catalyzed by biomimetic copper complex and N-hydroxyphthalimide (NHPI) under mild conditions

Abstract

A galactose oxidase-like copper complex (CuIIL) (Ligand: N, N′-bis(2-hydroxy-3,5-di-tert-butylphenyl)-2,2′-diaminobiphenyl) was synthesized and used to catalyze the aerobic oxidation of alkyl aromatics to ketones in presence of N-hydroxyphthalimide (NHPI). The catalytic system exhibited excellent performance and tolerance under mild conditions. Mechanistic studies indicated that NHPI could be activated smoothly to generate phthalimide N-oxyl (PINO) radical in the presence of CuIIL. The kinetic isotope effect (KIE) studies showed that the generation of PINO radical was the rate-determining step.