Dioxygen-triggered oxidation of benzylic C–H bonds: insight on the synergistic effect of Cu–Fe bimetallic oxide

Abstract

Chemists have been paying attention to the functionalization of C–H bonds towards value-added molecular scaffolds since C–H bonds are ubiquitous in organic compounds. Cubic Cu–Fe bimetallic oxide has been prepared by a facile hydrothermal method and catalytically investigated in aerobic oxidation of benzylic C–H bonds to ketones using N-hydroxyphthalimide (NHPI). The high catalytic performance can be ascribed to the significant effect of the coupled cations in the Cu–Fe bimetallic oxide catalyst in which the boosted redox property is the key to catalyzing the C–H oxidation. The bimetallic interaction between copper and iron was extensively scrutinized by powder XRD, Raman spectroscopy, XPS, and H₂-TPR techniques. The H₂-TPR results suggested that the redox property could be boosted by doping iron in CuO. The synergistic effect between Fe and Cu significantly accelerated the catalytic oxidation over Cu–Fe bimetallic oxide. To verify the wide applicability of the catalyst, several substrates have been thoroughly investigated.