Immobilized ionic liquid on γ-Fe2O3 as an efficient and reusable nanocatalyst for the synthesis of pyrano[2,3-d] pyrimidinone derivatives

In recent years, γ-Fe2O3 magnetic nanoparticles (MNPs) have been appeared as a new kind of efficient catalyst support due to low toxicity, ease of surface modification, unique physical properties including the high surface area and superparamagnetism. In order to prevent the aggregation of γ-Fe2O3 MNPs, its surface is usually modified with a silica layer, taking advantage of being biocompatible, hydrophilic and, also, because the surface of silanol groups can easily react with various organic and inorganic materials to achieve the certain purposes especially in the field of catalysis [1]. NPs, especially MNPs have appeared as a bridge between homogeneous and heterogeneous catalysts. The magnetic nature of these particles allows for easy recovery and recycling of the catalysts by an external magnetic field. To improve the chemical stability as well as to achieve some advantages as the versatility in surface modification, MNPs commonly coat with different organic or inorganic compounds and precious metals [2,3].In this work, γ-Fe2O3@SiO2@IL is prepared, characterized and used to synthesis of pyrano[2,3-d]-pyrimidinediones(thione) derivatives via a three-component reactionof different aromatic aldehydes, (thio)barbituric acid and malononitrile in a solution of water/ethanol. The structures of the products were characterized using FT-IR,1H NMR and 13C NMR spectroscopy. The present methodology suggests several advantages such as easy catalyst separation and high reusability for several consecutive runs without significant loss of its catalytic efficiency, high yields of obtained products, simple procedures, low cost and short reaction times (Scheme 1).