Quinoxaline synthesis via oxidative cyclization reaction using metal–organic framework Cu(BDC) as an efficient heterogeneous catalyst

• First Cu–MOFs catalysts for quinoxaline synthesis from α-hydroxyketones.
• Simple and practical protocols under air atmosphere in short reaction time.
• The catalyst can be facilely recovered and reused.

A metal–organic framework Cu(BDC) was synthesized, and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. The Cu(BDC) was employed as an efficient heterogeneous catalyst for the oxidative cyclization reaction between α-hydroxyacetophenone and phenylenediamine to form 2-phenylquinoxaline as the principal product. The optimal conditions involved the use of air atmosphere oxidant in toluene solvent at 100 °C in 3 h. In addition, the Cu(BDC) exhibited higher catalytic activity in the quinoxaline synthesis reaction than that of others Cu–MOFs such as MOF-199, MOF-118, and Cu2(BDC)2(DABCO), and higher than that of Mn(BDC), and Ni2(BDC)2(DABCO). The Cu(BDC) catalyst could be recovered and reused several times without a significant degradation in catalytic activity.

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