Magnetic DL-methionine grafted to chitosan by EDTA linker nanomaterial: a highly efficient multifunctional organocatalyst for the synthesis of highly substituted imidazole derivatives under green conditions

Abstract

In this research, a novel protocol for the synthesis of imidazole derivatives with various substitutions has been investigated in the presence of a new and highly effective magnetic decorated DL-methionine amino acid grafted onto the chitosan backbone by using EDTA linker (CS − EDTA − MET@Fe3O4) under green chemistry conditions. The CS − EDTA − MET@Fe3O4 nanocomposite was properly characterized by using FTIR, EDX, XRD, FESEM, TGA and VSM spectroscopic, microscopic, or analytical methods. The CS − EDTA − MET@Fe3O4 nanocomposite was used as a highly efficient heterogeneous organocatalyst for the synthesis of a wide range of three- and four-substituted imidazole derivatives, as an important pharmaceutical scaffold, through multicomponent reactioins (MCRs) strategy. The CS − EDTA − MET@Fe3O4 multifunctional nanocatalyst exhibited high catalytic activity, selectivity, and stability to promote the reactions of benzoin or benzyl, different aldehyde derivatives, and ammonim acetate as well as aromatic or aliphatic amine derivatives in EtOH as green solvent. Key advantages of the present protocol are high to excellent yields, the use of a low loading renewable, bio-based and biodegredable chitosan- as well as amino acid-based nanomaterial, and simple procedure for the preparation of CS − EDTA − MET@Fe3O4 nanomaterial and synthesis of a wide range of imoidazole derivatives. In addition, the catalyst's properties, including its magnetic properties and appropriate surface area characteristicscontribute to its excellent catalytic performance. Fuerthermore, the CS − EDTA − MET@Fe3O4 nanocatalyst can be used for up to six cycles for the preparation of imidazole derivatives with only a slight decrease in its catalytic activity.