TiCl2/Nano-γ-Al2O3 as a Novel Lewis Acid Catalyst for Promotion of One-pot Synthesis of 1,4-dihydropyridines

Synthesis of organic compounds using nano-catalysts is more and more attention due to the numerous advantages such as cost-effectiveness, high catalytic activity, ease of product separation, recovery of the catalyst, repeated recycling potential and good stability. In this work, TiCl2/nano-γ-Al2O3, as a novel type of green heterogeneous solid acid was prepared by the immobilization of TiCl2 on the surface of nano-γ-Al2O3 and characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX), X-ray fluorescence spectroscopy (XRF), Brunauer–Emmett–Teller (BET) and thermal gravimetric analysis (TGA). One-pot multicomponent reactions (MCRs) have been extensively studied for their simple procedures, high selectivity, and superior atom economy. The activity of TiCl2/nano-γ-Al2O3 was probed via the synthesis of 1,4-dihydropyridine derivatives of three components coupling reaction of aldehyde, 1,3-dicabonyl compound and ammonium acetate under solvent free condition with excellent yields in short time. The obtained 1,4-dihydropyridine derivatives were characterized by FT-IR and 1H NMR spectra.