A novel protocol for the synthesis of pyrano[2,3-h]coumarins in the presence of Fe3O4@SiO2@(CH2)3OCO2Na as a magnetically heterogeneous catalyst†
In this study, sodium carbonate functionalized silica coated-iron oxide nanoparticles (Fe3O4@SiO2@(CH2)3OCO2Na) were synthesized, characterized and applied as a heterogeneous basic nanocatalyst for the synthesis of pyrano[2,3-h]coumarins. The structure of this nanocatalyst was investigated using FT-IR, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) techniques. Fe3O4@SiO2@(CH2)3OCO2Na was used as a catalyst in the synthesis of pyrano[2,3-h]coumarin derivatives via a simple three-component reaction between 5,7-dihydroxy-4-methylcoumarin, dialkyl acetylenedicarboxylates, and various aromatic aldehydes. The nanocatalyst could be easily recovered by applying an external magnetic field and reused at least seven times without a significant change in its catalytic activity.