An efficient and recyclable heterogeneous catalytic system for the synthesis of 1,2,4-triazoles using air as the oxidant

Copper-zinc supported on Al2O3-TiO2 was found as a simple and efficient heterogeneous catalyst for the oxidative synthesis of 1,2,4-triazole derivatives using air as the green oxidant under ligand-, base- and additive-free conditions. The heterogeneous reactions carried out smoothly with a large range of substrates, including NO2-, vinyl-, pyrimidine- and imidazole- contained starting materials, and provided corresponding triazoles in moderate to excellent yields with low catalyst loading (1.6 mol%). Furthermore, the catalyst can be simply recycled many times without significant loss in catalytic activity.