In furtherance of our research on the green and environmentally benign synthesis of heterocyclic and pharmaceutical compounds, we now report a novel multicompo-nent route to amides via the condensation of arenes, 2-aminobenzimidazole, and cyclic anhydrides in the presence of crystalline nanoparticle nickel-ferrite silica-propyl supported glucosamine (NiFe2O4@SiO2-propyl@glucosamine, Figure 1) as an efficient, reusable and heterogeneous catalyst in water as green solvent. The NiFe2O4@SiO2-pro-pyl@glucosamine magnetic nanoparticles (MNPs) were synthesized in three steps from commercially available materials. MNPs were coated by silica using a sol-gel process which we have previously described. To check the efficiency of our new catalyst in organic reactions, the condensation of toluene (1.0 mmol), phthalic anhydride (1.0 mmol), and 2-aminobenzimidazole (1 mmol) was attempted with different catalysts in various solvents. None of the desired N-(l-hydro-benzodimidazole-2-yl)-2-(4-methylbenzoyl) benzoamide (6b) was obtained after stirring the reaction mixture for 24 h at room temperature in the absence of catalyst (Table 1, entry 1). The reactions were carried out in the presence of HCl, K-10, HY-zeolite, NiFe2O4, SiO2 and NiFe2O4@SiO2 and showed low yields of product 6b even after 5h (Table 2, entries 2-7). The yield of the product improved remarkably to 96 after stirring the components at room temperature for 1h in the presence of NiFe2O4@SiO2-propyl@glucosamine (Table I, entry 8). Entries 8-11 show that this mul-ticomponent reaction did not lead to the product 6b in weak polar solvents such as chloroform and dioxane, but the efficiency and the yield of the reaction in water were high.
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