Synthesis, characterization and catalytic application of silica supported tin oxide nanoparticles for synthesis of 2,4,5-tri and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions

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.…”

“…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 …”

Catalytic Synthesis of 1,2,4,5‐Tetrasubstituted 1H‐Imidazole Derivatives: State of the Art

“…In recent years, the use of silica-supported catalysts has received considerable attention and it has been shown that the synthesis of 1,2,4,5tetrasubstituted-1H-imidazoles from benzil (5), aldehydes, primary amines and AcONH4 can be catalyzed by perchloric acid adsorbed on silica gel, [52] silica-supported BF3, [53] silica-supported polyphosphoric acid, [54.55] 12-phosphotungstic acid (PWA)-supported on silica gel, [56] P2O5 supported on silica gel, [57] nano-TiCl4-SiO2, [58] silica supported SnO2, [59] HBF4×SiO2, [60] carboxylic acid functionalized porous silica nanoparticles, [61] silica coated magnetic NiFe2O4 nanoparticle supported phosphomolybdic acid, [62] silica supported Preyssler nanoparticles heteropolyacid, [63] SbCl3 adsorbed on silica gel, [64] concentrated HNO3 supported on nanosilica, [65] Bi(NO3)3×SiO2, [66] NaHSO4 supported on silica gel, [67] SbCl3 immobilized on silica gel (SiO2-OSbCl2), [68a] and K5CoW12O40 . 4H2O.…”

Homoselective synthesis of 5‐substituted 1H‐tetrazoles and one‐pot synthesis of 2,4,5‐trisubstuted imidazole compounds using BNPs@SiO2‐TPPTSA as a stable and new reusable nanocatalyst

“…For the synthesis of 2,4,5‐trisubstituted imidazoles, several protocols have been reported using catalysts such as nano Fe 3 O 4 @SiO 2 –OSO 3 H, [ 31 ] L‐proline, [ 32 ] montmorillonite K10, and nanosulfated zirconia, [ 33 ] zeolites and [EMIM]OAc, [ 34 ] graphene oxide–chitosan, [ 35 ] silica gel/NaHSO 4 , [ 36 ] MCM‐41, [ 37 ] Fe 3 O 4 @SiO 2 –OSO 3 H, [ 38 ] propylpiperazine N‐sulfamic acid, [ 39 ] NiCl 2 .6H 2 O with acidic alumina, [ 40 ] [HeMIM]BF 4 , [ 41 ] and CoFe 2 O 4 nanoparticles. [ 42 ]…”