An atomically dispersed Co catalyst for efficient oxidative fabrication of benzoheterocycles under ambient oxygen conditions

Abstract

The highly efficient synthesis of benzoxazole, benzothiazole and benzimidazole has attracted much attention due to their superior biological activities. However, developing environmentally friendly and poisoning-resistant catalysts in heterogeneous catalytic systems remains a critical challenge. Herein, an atomically dispersed Co₁/NC catalyst was fabricated by facile pyrolysis of a zeolitic imidazolate framework (ZnCo-ZIF). The Co₁/NC catalyst exhibited excellent oxidation catalysis, sulfur-resistance and reusability performance. The mass specific activity (MSA) of Co₁/NC was up to 42.0 mol_2-PBO mol_Co⁻¹ h⁻¹, much higher than that of the Co/NC nano-catalyst (15.6 mol_2-PBO mol_Co⁻¹ h⁻¹). Mechanism studies showed that O₂ was activated by atomically dispersed Co active species to form ¹O₂ and ˙O₂⁻, which were responsible for the dehydrogenation of the key imine intermediates to produce 2-phenylbenzoxazole (2-PBO). The current work represents a novel feasible strategy for the synthesis of bioactive heterocyclic compounds using efficient, stable and green heterogeneous catalysts.