Sustainable Nanoporous Benzoxazole Networks as Metal-Free Catalysts for One-Pot Oxidative Self-Coupling of Amines by Air Oxygen

Abstract

The development of sustainable organocatalysts with porosity, high stability, and excellent catalytic activity offers a clean and green alternative to precious metal catalysts. Here, an efficient, nanoporous, heterogeneous benzoxazole catalyst is reported for aerobic oxidative coupling of amines. A molecular design strategy is presented to functionalize primary amines to produce valuable products under one-pot, open-air reaction conditions. Unprecedented and previously unknown, the stable imine intermediate catalyzes its own formation, also known as autocatalysis, enabling a direct and favorable access to amino acids, even if the catalysts are absent. The biomimetic benzoxazole catalysts developed here provide quantitative catalytic activity over 50 cycles with favorable kinetics with no degradation. This work also marks the first use of benzoxazoles for oxidative catalytic reactions.