Highly Efficient, Four Component, One-pot Synthesis of Tetrasubstituted Imidazoles Using a Catalytic Amount of FeCl3 · 6H2O

One-pot synthesis of multisubstituted imidazoles catalyzed by Dendrimer-PWAn nanoparticles under solvent-free conditions and ultrasonic irradiation

“…The effect of temperature was also studied by carrying out the model reaction in the presence of 0.035 g of the catalyst at room temperature, 60, 80 and 100°C under solvent-free conditions. It was observed that the corresponding products were obtained in 27, 61, 91 and 96 % yields, respectively ( Table 2, entries [16][17][18][19], and the best results were obtained at 90°C ( Table 2, entry 5).…”

“…Generally, trisubstituted imidazoles are synthesized by the condensation of 1,2-diketones, an aldehyde and ammonium acetate by using various catalysts such as: InCl 3 Á3H 2 O [6], Yb(OTf) 3 [7], TBAB [8], Fe 3 O 4 @SiO 2 -Imid-PMA n [9], Nanocrystalline MgAl 2 O 4 [10], Ferric(III) nitrate supported on kieselguhr [11], SBA-15/2,2,2-trifluoroethanol [12], and HOAc [13]. 1,2,4,5-tetrasubstituted imidazoles are synthesized by the condensation of 1,2-diketones, an aldehyde, ammonium acetate and primary amine in the presence of various catalysts such as silica gel or silica gel/NaHSO 4 [14], K 5 CoW 12 O 40 .3H 2 O [15], HY zeolite [16], Fe 3 O 4 @SiO 2 -Imid-PMA n [9], trifluoroethanol [12], HClO 4 -SiO 2 [17], heteropolyacids [18], FeCl 3 .6H 2 O [19], 1-Butyl-3-methylimidazolium bromide [20], trityl chloride [21], tetrabutyl ammonium bromide [22], alumina [23], 1,4-diazabicyclo [2,2,2]octane (DABCO) [24], nano-TiCl 4 ÁSiO 2 [25], PPA-SiO 2 [26], nanocrystalline sulfated zirconia (SZ) [27] and silica-bonded propylpiperazine N-sulfamic acid (SBPPSA) [28]. However, some of these synthetic methods have limitations such as harsh reaction conditions, use of hazardous chemicals with often expensive acid catalysts, complex working and purification procedures, long reaction times, and moderate yields.…”

Synthesis of α,β‐Diketotriazoles by Aerobic Copper‐Catalyzed Oxygenation with Triazole as an Intramolecular Assisting Group

“…Imidazoles 8 and 9 were prepared by known procedures (Scheme 5). [2,24] The exact structure of 9 was determined by X-ray crystallography.…”

Current advances in the synthesis and biological potencies of tri- and tetra-substituted 1H-imidazoles

“…Several catalyzed reactions were published for the synthesis of 1,2,4,5-tetra-substituted imidazoles using catalysts such as Y(NO 3 [100], bioglycerol-based recyclable carbon catalyst [102], Amberlyst A-15 [110], SBA-15/TFE (SBA-15/2,2,2-trifluoroethanol) [112], SBA-Pr-SO 3 H [113], silicasupported tin oxide nanoparticles [114], magnetic Fe 3 O 4 nanoparticles [119], L-proline [121], p-toluene sulfonic acid (PTSA) [126], solvent-free conditions with sodium dihydrogen phosphate [128], microwave irradiation [141][142][143], FeCl 3 ·6H 2 O [178], fluoroboric acid adsorbed on silica-gel (HBF 4 -SiO 2 ) [179], NHC (N -Heterocyclic Carbene) [180], trifluoroacetic acid [181], a novel organometallic catalyst (PSNP-CA) [182], MCM-41 [183], nano-TiCl 4 ·SiO 2 [184], and clay-supported titanium catalyst [185]. Highly substituted imidazole derivatives can be created using a new four-component and three-step reaction from alkoxyallenes, amines, iodine and nitriles with excellent yields.…”