NiO@HNTs-SO3H as a new heterogeneous catalyst for the green and efficient one-pot synthesis of 1-(benzothiazolylamino) methyl-2-naphthols and tetrahydrobenzo[b]pyrans

Abstract

NiO nanoparticles were assembled on the surface of Halloysite nanotubes, which were subsequently further functionalized by sulfonic acid, to create NiO@HNTs-SO₃H composite. This composite is employed as a heterogeneous catalyst in the one-pot synthesis of 1-(benzothiazolylamino) methyl-2-naphthols starting from aryl aldehyde, β-naphthol and 2-aminobenzothiazole as well as Tetrahydrobenzo[b]pyrans starting from aldehyde, dimedone and malononitrile. The catalyst was examined using Fourier transform infrared (FT-IR), energy dispersive X-ray (EDX), X-ray diffraction (XRD) pattern, and scanning electron microscopy (SEM) images. The synthesized organic compounds were examined using ¹H NMR and ¹³C NMR spectroscopy and mass analysis by HRMS. The most notable benefits of the current work are its straightforward setup, gentle reaction conditions, green solvents, excellent yields, ease of purification, high efficiency, and the use of a recoverable and environmentally friendly catalyst. The easy separation and reusability of NiO@HNTs-SO₃H catalyst after five runs confirmed the stability and effectiveness of the catalyst.

Graphical Abstract