An amino-triethoxysilylpropyl-tetrazole-carboxamide-based Mn-complex as a capable nanocatalyst for the synthesis of tetrahydrobenzopyrans

Abstract

A novel magnetic supported amino-triethoxysilylpropyl-tetrazole-carboxamide (ATSPTC) based Mn complex (the ATSPTC-Mn catalyst) as a heterogeneous catalyst was designed, prepared, and characterized by the Fourier-Transform Infrared spectroscopy (FT-IR), Energy-Dispersive X-ray spectroscopy (EDX), X-ray powder Diffraction (XRD), Thermo-Gravimetric Analysis-Differential Thermal Analysis (TGA-DTA), Vibrating Sample Magnetometry (VSM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), SEM-mapping and Inductively Coupled Plasma (ICP) techniques. Then, the ATSPTC-Mn catalyst was used as a reusable catalyst for the green synthesis of tetrahydrobenzopyrans from the three-component condensation reaction of aryl aldehydes, dimedone, and malononitrile in refluxing ethanol. It was also found that the ATSPTC-Mn catalyst has high efficiency in the synthesis of ordinary tetrahydrobenzopyrans as well as the bis and tris derivatives. The catalyst can be easily recovered by a magnetic field and reused for seven consecutive reaction cycles without significant loss of activity.