Green Oxidation of Indoles Using Molecular Oxygen over a Copper Nitride Nanocube Catalyst

Oxidative transformation of indoles is a promising approach for synthesizing valuable nitrogen-containing compounds; however, conventional methods use toxic oxidants and additives. Herein, we report for the first time the catalytic oxidative trimerization and the oxygenative cleavage (Witkop oxidation) of indoles using molecular oxygen under additive-free conditions accomplished by a copper nitride nanocube (Cu3N NC) catalyst. The Cu3N NC catalyst exhibits excellent activity to produce various indolin-3-ones and 2-ketoanilides with high functional group tolerance. Owing to this excellent catalytic performance, the Cu3N NC catalyst is distinguished from the conventional copper catalysts, demonstrating the high catalytic potential of metal nitride in organic synthesis.

Automated summary

In this study, the catalytic oxidative trimerization and oxygenative cleavage reactions of indoles were achieved using a copper nitride nanocube catalyst, producing valuable nitrogen-containing compounds such as indolin-3-ones and 2-ketoanilides under additive-free conditions.