Solvent-free synthesis of tetrasubstituted imidazoles on silica gel/NaHSO4 support

Microwave Assisted Synthesis of 2-Amino-3,4,5-Trisubstituted Imidazolines Using Radiszewski Method, Their Characterisation and Evaluation for Antioxidant Activity

“…[1][2][3][4][5][6][7][8] The fundamentals of microwave-assisted organic synthesis in polar solvents are also reported, which have supported in the development of relatively sustainable procedures for the synthesis of drugs and fine chemicals. [9][10][11] Bearing in mind that most biologically potent compounds are heterocyclic in nature and their importance in medicinal chemistry to identify leads and to modify structures, therefore it is confirmed from above discussion that the applications of microwaves will certainly increase in the future.…”

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

“…Inorganic or organic matrixsupported catalysts and nano catalysts (bioglycerol-based carbon catalysts) [102], nano-SnCl 4 ·SiO 2 [103], BF 3 -SiO 2 [104], HClO 4 -SiO 2 [105], NaHSO 4 /silica gel [106], silica sulfuric acid [107], NiCl 2 ·6H 2 O/Al 2 O 3 [108], HBF 4 -SiO 2 [109], Amberlyst A-15 [110], polymer-supported ZnCl 2 [111], SBA-15/TFE (SBA-15/2,2,2-trifluoroethanol) [112], SBA-Pr-SO 3 H [113], silica-supported tin oxide nanoparticles (SiO 2 :SnO 2 ) [114], ferric(III) nitrate supported on kieselguhr (Fe(NO 3 )3-Kie) [115], zeolite-supported reagents [116], nanocrystalline MgO [117], nano-crystalline sulfated zirconia [118], magnetic Fe 3 O 4 nanoparticles [119], heteropolyacids [120] organocatalysts, such as L-proline [121], DABCO [122], enzymes (e.g., Lipase [123], papain [124]), trichloromelamine [125]), p-toluene sulfonic acid [126], ammonium chloride (NH 4 Cl) [127], NaH 2 PO 4 [128], mercaptopropylsilica [129], sodium bisulfate [130], ceric ammonium nitrate [131], morpholinium hydrogen sulphate [132], diethyl ammonium hydrogen phosphate [133], sulfated tin oxide [134], urea/hydrogen peroxide [135], silicabound propylpiperazine N -sulfamic [136], tetrabutylammonium bromide (TBAB) [137], sodium bisulfate [128], potassium aluminum sulfate (alum) [138], l-cysteine …”

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

“…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.…”