Synthesis of new 2-amino-4H-pyran-3,5-dicarboxylate derivatives using nanocrystalline M^sup II^Zr^sub 4^(PO^sub 4^)^sub 6^ ceramics as reusable and robust catalysts under microwave irradiation

Abstract In the present paper, we report the successful synthesis of nanocrystalline M^sup II^Zr^sub 4^(PO^sub 4^)^sub 6^ ceramics (M: Mn, Ni, Fe, Co). These nano-structures were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer (VSM). Size of nano-structures was in the range of 20-150 nm. Nano-M^sup II^Zr^sub 4^(PO^sub 4^)^sub 6^ as an efficient and green catalyst has been used for the preparation of 2-amino-4H-pyran-3,5-dicarboxylate derivatives by the three-component condensation reaction of ethyl cyanoacetate, ethyl acetoacetate, and various aromatic aldehydes under microwave irradiation. Extraordinarily, the best results were obtained using MnZr^sub 4^(PO^sub 4^)^sub 6^ nanocrystallines as an efficient catalyst. This method provides several advantages including easy work-up, excellent yields, short reaction times, using of microwave as green method, recoverability of the catalyst, and little catalyst loading. Graphical abstract [Figure not available: see fulltext.]