Abstract
Abstract In this work, magnetic nanoparticle-supported sulfonic acid (γ-Fe2O3-SO3H) is used as an efficient catalyst in the synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5-tetrasubstituted imidazoles in a short time (40–70 min for trisubstituted imidazoles and 30–40 min for tetrasubstituted imidazoles) and high-purity products were obtained (92–98% for trisubstituted imidazoles and 94–98% for tetrasubstituted imidazoles) in simple multicomponent reactions. The structure of these products was confirmed via FT-IR and NMR. Green and recyclable catalysts, eco-friendly and solvent-free conditions, high catalytic activity, shorter reaction time, easy recovery by an external magnet, high purity, and excellent yields are some features of these reactions.
Highlights
Due to the effects of the chemical industry on the environment since the 1940s, fundamental changes have beenMulticomponent reactions (MCRs) have applications in organic and medicinal chemistry that produce complex products from simple substances in one-pot processes
According to the importance of green chemistry goals, in this project, we use magnetic particle-supported sulfonic acid (γ-Fe2O3-SO3H) [13] as a recyclable catalyst in the synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5tetrasubstituted imidazoles, which are valuable biologically active compounds [14], in a simple one-pot procedure from which substituted imidazoles were obtained with high efficiency and purity
To optimise the reaction conditions for the preparation of 2,4,5-trisubstituted imidazoles, condensation of benzil (1 mmol), ammonium acetate (5 mmol) and benzaldehyde (1 mmol) in the presence of the γ-Fe2O3-SO3H catalyst (10 mol%) under solvent-free conditions was selected as a model reaction (Scheme 1)
Summary
Due to the effects of the chemical industry on the environment since the 1940s, fundamental changes have been. According to the importance of green chemistry goals, in this project, we use magnetic particle-supported sulfonic acid (γ-Fe2O3-SO3H) [13] as a recyclable catalyst in the synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5tetrasubstituted imidazoles, which are valuable biologically active compounds [14], in a simple one-pot procedure from which substituted imidazoles were obtained with high efficiency and purity. To optimise the reaction conditions for the preparation of 2,4,5-trisubstituted imidazoles, condensation of benzil (1 mmol), ammonium acetate (5 mmol) and benzaldehyde (1 mmol) in the presence of the γ-Fe2O3-SO3H catalyst (10 mol%) under solvent-free conditions was selected as a model reaction (Scheme 1). An investigation was performed to optimise the amount of ammonium acetate used in this reaction under solvent-free conditions, and the best result was achieved with 5 mmol ammonium acetate (Table 4, entry 3). Similar results were obtained for the synthesis of tetrasubstituted imidazoles from combinations of differently substituted aromatic aldehydes and amine derivatives (Table 6). 219–221 [9] 252–254 [24] 171–173 [9] 180–182 [25] 185–187 [26] 193–195 [27] 186–188 [27] 242–245 [28] 196–198 [28] 285–287 [9] 148–150 [29] 222–225 [9] 196–198 [9] 155–157 [9] 220–222 [9] 229–231 [9] 182–185 [26] 169–170 [26]
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