Synthesis of benzothiazole and benzimidazole derivatives via an eco-friendly method using piperazine immobilized on nano-ZnO-sulfuric acid as a powerful catalyst

In this research, the synthesis of piperazine immobilized on nano-ZnO-sulfuric acid (PINZS) as a new piperazine-based nano-reagent is reported. After identification of PINZS using different techniques including XRD (X-ray powder diffraction), TGA (thermogravimetric analysis), FT-IR (Fourier transform infrared spectroscopy), FESEM (field emission scanning electron microscopy), and EDX (energy-dispersive X-ray) analysis, this reagent is efficiently used for the synthesis of 1-(benzothiazolylamino) phenylmethyl-2-naphthols and pyrimido[1, 2-a]benzimidazoles via a domino Knoevenagel/Michael sequence which identified acceptable reaction times (7-45 min.), great yields (up to 98%) and ease of the preparation, separation, and recovery of PINZS (for three times) as the most important features of this protocol. [GRAPHICS] .