Synthesis of Benzoxazoles by Metal‐Free Oxidative Cyclization of Catechols with Amines

Abstract

Benzoxazoles are crucial in pharmaceuticals, agrochemicals, and functional materials. Their simple, economical, green, and efficient synthesis has attracted long‐standing interest in synthetic chemistry. Herein, we present an extremely simple strategy for constructing benzoxazoles via the direct oxidative cyclization of readily available catechols and primary amines, using DDQ/EA and O₂/water oxidative systems, respectively. The DDQ/EA system demonstrates distinct advantages in substrate and functional group compatibility. In contrast, the O₂/water system, which is milder, greener, and more economical, excels in synthesizing C‐2 alkyl‐substituted benzoxazoles. Overall, these two systems provide complementary advantages and are both well‐suited for gram‐scale synthesis. Given its high simplicity and practicality, this strategy could serve as a promising alternative in benzoxazole synthesis.