Visible-light-mediated aerobic oxidation of toluene via V2O5@CN boosting benzylic C(sp3)-H bond activation

Incorporating photocatalysis into benzylic C(sp(3))-H oxidation represents a recent advance of organic synthesis in a sustainable manner. Although photoinduced charge carriers enable the C(sp(3))-H bond to be activated under mild conditions, the reaction scale and activity remain hindered by the photoactivation efficiency. Herein, we present that the 1.0% V2O5@CN photocatalyst, a visible-light-active C3N4- based material, is striking active for the aerobic oxidation of benzylic C(sp(3))-H bonds, affording a conversion rate 11.6 times higher than that of independent CN. The enhanced activity and C(sp(3))-H bond photoactivation, as well as the induction period shortening and active period acceleration, are rationalized by the low-EVB hole injection from V2O5 into CN and the boosted charge separation. The durability and utility are affirmed in multiple catalytic cycles, scalable long-term reactions, and available substrate scopes. Reactive intermediate studies by EPR demonstrate the involvement of (CH2Ph)-C-center dot, O-center dot(2), and (OH)-O-center dot radicals in photoredox catalysis. The mechanism that causes the change of main product species is attributed to the formation of (OH)-O-center dot in the later reaction stage. This work indicates a unique photoactive V2O5@CN catalysis mode, opening up the efficient use of CN in scalable photocatalytic toluene oxidation. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study introduces a novel visible-light catalyst, V2O5@CN, with high catalytic activity and efficiency in the oxidation of benzylic C(sp(3))-H bonds. The rapid photoactivation of benzylic C(sp(3))-H bonds was achieved through low-EVB hole injection and enhanced charge separation, leading to an efficient pathway for sustainable organic synthesis.