The tannic acid–based iron nanoparticle (TAN-Fe-NP) was prepared by a redox reaction between tannic acid and FeCl3 in water and characterized by the Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, energy dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Then, a TAN-Fe-NP nanocatalyst was used as an efficient catalyst for the synthesis of polyhydroquinolines from the reaction of ethyl acetoacetate, benzaldehydes, dimedone, and ammonium acetate in ethanol at 60 °C in high yields and low reaction times. Since this catalyst is made of natural materials, it has a great advantage compared with the other catalysts and is cheap, available, natural, safe, nontoxic, and eco-friendly as well.
