Synthesis of Polysubstituted Pyridines via Nitrogen-doped Graphene Catalyzed One-Pot Multicomponent Reaction under Solvent-Free Conditions

Abstract

: Polysubstituted pyridine derivatives were producedwith high to excellent yields in the presence of nitrogen-doped graphene (NDG) as a dual acid–based catalyst. NDG efficiently catalyzes the multicomponent reaction between arylaldehydes, diethyl-acetylene dicarboxylates, malononitrile, and ammonium acetate under solvent-free conditions at 80°C to afford the polysubstituted pyridines in short reaction times. The structures of the synthesized pyridines were established by Ft-IR, 1H, and 13C NMR spectroscopic analysis. The advantages of this method include the in-situ oxidation of prepared 1,4-dihydropyridines, one-pot procedure, solventless system, operational simplicity, and no column chromatography. Additionally, neither toxic solvents nor catalysts are needed, and the procedure can be very reliable among the reported methodologies. The yields and reaction times in the presence of four times recycled catalyst are in comparable to the fresh catalyst. background: Graphene quantum dots have attracted considerable attention of chemists because of their unique properties such as: stability, non-toxicity, good water solubility, biocompatibility. In continuation of our interest in using ionic liquids, water or solvent-free systems as green reaction media in organic reactions for the synthesis of important compounds , we wish to report here efficient synthesis of polysubstituted pyridine derivatives in high to excellent yields using Nitrogen-doped graphene as efficient catalyst.