Nano-eggshell/B(III)as a highly efficient heterogeneous catalyst for the synthesis of 1,3-oxazines in aqueous media, along with DFT simulations

Abstract

In the present study, a convenient and greener synthesis of a series of naphtho[1,2- e ][1,3]oxazines was accomplished via three-component one-pot cyclocondensation between β -naphthol, formaldehyde, and various amines using nano-eggshell/B(III) as a natural catalyst in aqueous medium. The Lewis acid nano-eggshell/B(III) catalyst was investigated by techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), mapping, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). This approach is totally non-polluting and several advantages, such as shorter reaction time, mild reaction conditions, simple workup, and reduced environmental impact. The experimental results are consistent with the data obtained from the DFT calculations.