Synthesis of dihydropyrano[2,3-c]pyrazoles using Ca9.5Mg0.5(PO4)5.5(SiO4)0.5F1.5 as a new nano cooperative catalyst

Abstract

Ca9.5Mg0.5(PO4)5.5(SiO4)0.5F1.5 was used as a nano cooperative catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles derivatives via a one-pot four component reaction of aldehyde, ethyl acetoacetate, malononitrile and hydrazine hydrate. The reactions were carried out at 70 °C under mild and heterogeneous conditions. The catalyst was easily synthesized by high energy ball milling and the effect of some parameters such as specific surface area, pore volume, particle size, pH and crystallinity degree of the catalyst was studied on the yield and reaction time. The used catalyst showed both Bronsted base and Lewis acid properties. The acidic sites were determined by FT-IR spectroscopy of pyridine adsorption technique at different temperature. Using a new cooperative catalyst and an environmentally benign procedure, good to high yield of the products and relatively short reaction time were the advantages of the present method.