Novel ferrocene substituted benzimidazolium based ionic liquid immobilized on magnetite as an efficient nano-catalyst for the synthesis of pyran derivatives

Abstract

Due to the attractive applications of functionalized ionic liquids (ILs) based on benzimidazolium as catalysts or solvents in the chemical reactions and also the wide applications of benzimidazole-based compounds in the medicinal chemistry; we designed and synthesized a new ferrocenyl-benzimidazolium salt for the first time. In this study, a novel magnetically recoverable Fe3O4@SiO2-BenzIm-Fc[Cl]/NiCl2 nanoparticle was also synthesized using a simple chemical coprecipitation approach. The synthesized nanoparticle was characterized by Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM) techniques and field emission scanning electron microscopy (FE-SEM). The catalytic activities of the novel magnetic nanoparticle were evaluated in the one-pot three-component synthesis of a wide variety of pyran derivatives under ultrasonic irradiation. New five component reactions were designed for the synthesis of novel asymmetric bis-pyran derivatives in the presence of catalytic amount of Fe3O4@SiO2@BenzIm-Fc[Cl]/NiCl2 nanoparticle under ultrasonic. The new catalytic method exhibits some notable advantages such as short reaction times, operational simplicity, green reaction conditions, high yields, and easy work-up and purification steps. In addition, the novel magnetic nanoparticle could be easily separated by an external magnet and reused for six times without significant loss of its catalytic activity in the reaction.