- Ag–TiO2 nanocomposite-catalyzed one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles: a green and benign approach
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Ag–TiO2 nanocomposite as an efficient catalyst was synthesized and characterized by AFM analysis. This nanocomposite acts as a heterogeneous and recyclable catalyst for the room temperature synthesis of 1,2,4,5-tetrasubstituted imidazoles from aldehydes, benzil, ammonium acetate and several anilines or aliphatic amines via one-pot four-component condensation reaction in H2O as a green solvent. Ag–TiO2 nanocomposite was simply recovered by filtration and was reused up to three times.
- Alipour, Soghra,Vahdat, Seyed Mohammad,Chekin, Fereshteh
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p. 2315 - 2321
(2021/05/27)
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- Acid-Catalyzed 1,3-Dipolar Cycloaddition of 2 H-Azirines with Nitrones: An Unexpected Access to 1,2,4,5-Tetrasubstituted Imidazoles
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The first 1,3-dipolar cycloaddition of 2H-azirines with nitrones, a straightforward approach toward the regioselective synthesis of 1,2,4,5-tetrasubstituted imidazoles, is reported. This trifluoroacetic acid-catalyzed protocol tolerates a broad range of aliphatic and aromatic substrates, offering an efficient access to highly diverse, multisubstituted imidazoles in isolated yields up to 83% under mild conditions.
- Angyal, Anikó,Demjén, András,W?lfling, János,Puskás, László G.,Kanizsai, Iván
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p. 3587 - 3595
(2020/03/10)
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- STABLE PLY(IMIDAZOLIUM) HYDROXIDES
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Provided herein are imidazolium polymers having steric hindrance at the 4-position of the imidazole moieties in the polymeric chain. The sterically-protected, N-methylated imidazolium polymers exhibit hydroxide stability in concentrated caustic solutions at elevated temperatures, such as at 100 °C and higher.
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-
Page/Page column 30-31
(2018/02/28)
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- One-pot synthesis of multisubstituted imidazoles catalyzed by Dendrimer-PWAn nanoparticles under solvent-free conditions and ultrasonic irradiation
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An efficient, green and eco-friendly protocol has been developed for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles via one-pot condensation reaction using Dendrimer-PWAn as catalyst under solvent-free conditions or ultrasonic irradiation in excellent yields. The reactions under conventional heating conditions were compared with the ultrasonic-assisted reactions. The operational simplicity, practicability and applicability of this protocol to various substrates make it an interesting alternative to previous procedures. The present methodology offers several advantages such as excellent yields, short reaction times, a cleaner reaction, and the absence of any tedious work-up or purification. The catalyst is easily separated from the products by filtration and also exhibits remarkable reusable activity. SEM, BET and DLS of the catalyst were also investigated after each reaction cycle.
- Esmaeilpour, Mohsen,Javidi, Jaber,Dehghani, Farzaneh,Zahmatkesh, Saeed
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p. 163 - 185
(2017/01/14)
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- A new more atom-efficient multi-component approach to tetrasubstituted imidazoles: One-pot condensation of nitriles, amines and benzoin
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A new more atom-efficient multi-component approach for the synthesis of tetrasubstituted imidazoles via the one-pot condensation of nitriles, primary amines and benzoin has been described. Using this method, a wide range of structurally diverse nitriles and primary amines were successfully condensed with benzoin in glycerol in the presence of TFA under microwave irradiation at 120 °C and all the products were obtained in good to excellent yields with higher atom efficiencies in comparison with the commonly used four-component condensation of aldehydes, ammonium acetate, primary amines and benzil.
- Khalafi-Nezhad, Ali,Shekouhy, Mohsen,Sharghi, Hashem,Aboonajmi, Jasem,Zare, Abdolkarim
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p. 67281 - 67289
(2016/07/30)
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- One-pot synthesis of multisubstituted imidazoles under solvent-free conditions and microwave irradiation using Fe3O4@SiO2-imid-PMAn magnetic porous nanospheres as a recyclable catalyst
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An efficient, green and ecofriendly procedure has been developed using Fe3O4@SiO2-imid-PMAn as a magnetic catalyst for a rapid and improved synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions and microwave irradiation in excellent yields. The reactions under conventional heating conditions were compared with the microwave-assisted reactions. The operational simplicity, practicability and applicability of this protocol to various substrates make it an interesting alternative to previous procedures. The present approach offers several advantages such as short reaction times, high yields, simplicity of operation, easy work-up, a cleaner reaction and ease of recovery and reusability of the catalyst using a magnetic field. Also, the nanocatalyst can be easily recovered by the application of a magnetic field and reused for the next reactions at least 5 times without distinct deterioration in catalytic activity. SEM, BET, DLS and leaching of the catalyst after each reaction cycle were investigated.
- Esmaeilpour, Mohsen,Javidi, Jaber,Zandi, Maryam
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p. 3388 - 3398
(2015/05/20)
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- Imidazolium Cations with Exceptional Alkaline Stability: A Systematic Study of Structure-Stability Relationships
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Highly base-stable cationic moieties are a critical component of anion exchange membranes (AEMs) in alkaline fuel cells (AFCs); however, the commonly employed organic cations have limited alkaline stability. To address this problem, we synthesized and characterized the stability of a series of imidazolium cations in 1, 2, or 5 M KOH/CD3OH at 80 °C, systematically evaluating the impact of substitution on chemical stability. The substituent identity at each position of the imidazolium ring has a dramatic effect on the overall cation stability. We report imidazolium cations that have the highest alkaline stabilities reported to date, >99% cation remaining after 30 days in 5 M KOH/CD3OH at 80 °C.
- Hugar, Kristina M.,Kostalik, Henry A.,Coates, Geoffrey W.
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supporting information
p. 8730 - 8737
(2015/07/27)
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- Nano Fe3O4: A novel and magnetically recyclable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles in solvent-free conditions
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A convenient and efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles using nano Fe3O4 as magnetically recyclable catalyst is reported. The results show that the methodology has several advantages such as low loading of catalyst, excellent yield, short reaction time, operational simplicity and solvent-free conditions.
- Montazeri, Naser,Pourshamsian, Khalil,Rezaei, Hamideh,Fouladi, Mahdi,Rahbar, Sasan
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p. 3463 - 3466
(2013/04/24)
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- Triarylimidazole redox catalysts: Electrochemical analysis and empirical correlations
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A series of triarylimidazoles was synthesized and characterized electrochemically. The synthetic route is general, providing a pathway to 30 redox mediators that exhibit a > 700 mV range of accessible potentials. Most of the triarylimidazoles display three oxidation peaks where the first redox couple is quasi-reversible. The electronic character of the substituents affects the oxidation potential. This is exemplified by a linear correlation between the first oxidation potential and the sum of the Hammett σ+ substituent constants, as well as with a series of calculated ionization potentials. We close by putting forward a rule of thumb stating that for a given mediator, the upper limit of accessible potentials can be extended by at least 500 mV beyond the largest recorded value. A rationale, the conditions under which the rule is likely to apply, and an example are provided.
- Zhang, Ni-Tao,Zeng, Cheng-Chu,Lam, Chiu Marco,Gbur, Randi K.,Little, R. Daniel
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p. 2104 - 2110
(2013/04/23)
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- Efficient multi-component synthesis of highly substituted imidazoles utilizing P2O5/SiO2 as a reusable catalyst
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Phosphorus pentoxide supported on silica gel (P2O 5/SiO2) has been used as an efficient and reusable catalyst for the one-pot pseudo four-component synthesis of 2,4,5-trisubstituted imidazoles from benzil or benzoin, aldehydes, and ammonium acetate. It was also used for four-component preparation of 1,2,4,5-tetrasubstituted imidazoles from benzil or benzoin, aldehydes, primary amine, and ammonium acetate under thermal solvent-free conditions. The remarkable features of this new procedure are high conversions, cleaner reaction, simple experimental and work-up procedures and also the catalyst can be easily separated from the reaction mixture and reused several times without any loss of its activity.
- Shaterian, Hamid Reza,Ranjbar, Mohammad,Azizi, Kobra
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experimental part
p. 1635 - 1645
(2012/01/06)
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- Synthesis of highly substituted imidazoles using Bronsted acidic ionic liquid, triphenyl(propyl-3-sulphonyl)phosphonium toluenesulfonate, as reusable catalyst
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Bronsted acidic ionic liquid, triphenyl(propyl-3-sulphonyl) phosphonium toluenesulfonate, has been used as an efficient and reusable catalyst for the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions in excellent yields.
- Shaterian,Ranjbar,Azizi
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experimental part
p. 1120 - 1134
(2012/02/04)
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- One-pot synthesis of tetrasubstituted imidazoles catalyzed by preyssler-type heteropoly acid
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A simple one-pot four-component synthetic method was reported for the preparation of tetrasubstituted imidazole derivatives from benzil, aromatic aldehydes, primary amines and ammonium acetate in the presence of Preyssler-type heteropoly acid catalyst. This method was proved to be ecobenign, easy work-up, convenient, relatively short reaction times and the products were isolated with high yields.
- Javid, Ali,Heravi, Majid M.,Bamoharram,Nikpour, Mohsen
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experimental part
p. 547 - 552
(2012/02/16)
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- Direct arylation of simple azoles catalyzed by 1,10-phenanthroline containing palladium complexes: An investigation of C4 arylation of azoles and the synthesis of triarylated azoles by sequential arylation
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Direct triarylation and sequential triarylation reactions of simple azoles catalyzed by [Pd(phen)2]PF6 are described. Simple azoles, such as N-methylimidazole, thiazole, and oxazole, were observed to undergo triaryaltion reactions even at their C4 positions when treated with aryl iodides in the presence of [Pd(phen)2]PF6 as a catalyst and a stoichiometric amount of Cs2CO3 in DMA at 150 °C. Using excess amounts of azoles, selective C5 monoarylation was achieved by using the same catalytic system. Subsequent efforts demonstrated that C5 arylated azoles undergo exclusive C2 arylation using [Pd(phen)2]PF6 as the catalyst with galvinoxyl as an additive. Finally, unprecedented C4 arylation reactions of 2,5-diaryl-azoles occur by using the new catalytic system to give the corresponding triarylated products in good to excellent yields. The results of mechanistic studies suggest that the C2 arylation process takes place by way of an electrophilic aromatic substitution (SEAr) palladation pathway, while arylation reactions at the C4 position occur via a SEAr palladation and/or radical mechanism. Finally, a concise, three-step synthesis of the Tie-2 Tyrosine Kinase Inhibitor has been executed starting with commercially available N-methylimidazole by a route that employs the new sequential arylation process.
- Shibahara, Fumitoshi,Yamaguchi, Eiji,Murai, Toshiaki
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p. 2680 - 2693
(2011/06/20)
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- One-pot synthesis of tri- and tetra-substituted imidazoles using sodium dihydrogen phosphate under solvent-free conditions
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Sodium dihydrogen phosphate (NaH2PO4) efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.
- Karimi-Jaberi, Zahed,Barekat, Mohammad
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experimental part
p. 1183 - 1186
(2011/10/04)
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- l-Proline: an efficient catalyst for the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles
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A simple highly versatile and efficient synthesis of 2,4,5-trisubstituted imidazoles is achieved by three-component cyclocondensation of 1,2-dicarbonyl compound, aldehyde and ammonium acetate using l-proline as a catalyst in methanol at moderate temperature. To explore the utility of this method 1,2,4,5-tetrasubstituted imidazoles were also synthesized. The key advantages of this process are high yields, cost effectiveness of catalyst, easy work-up and purification of products by non-chromatographic methods.
- Samai, Subhasis,Nandi, Ganesh Chandra,Singh, Pallavi,Singh
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experimental part
p. 10155 - 10161
(2010/02/27)
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- An efficient and one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by InCl3·3H2O
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InCl3·3H2O was found to be a mild and effective catalyst for the efficient, one-pot, three component synthesis of 2,4,5-trisubstituted imidazoles at room temperature. Moreover, the utility of this protocol was further explored conveniently for the one-pot, four component synthesis of 1,2,4,5-tetrasubstituted imidazoles in high yields.
- Das Sharma, Saikat,Hazarika, Parasa,Konwar, Dilip
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p. 2216 - 2220
(2008/09/18)
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- Highly efficient, four component, one-pot synthesis of tetrasubstituted imidazoles using a catalytic amount of FeCl3 ? 6H2O
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An efficient and improved procedure for the synthesis of tetrasubstituted imidazoles by FeCl3 ? 6H2O catalyzed four-component one-pot synthesis in refluxing ethanol is described.
- Heravi, Majid M.,Derikvand, Fatemeh,Haghighi, Masoumeh
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- Photochemistry of N-heterocycles. 7: Light induced reductive ring contractions of sixmembered cyclic iminium ions
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Photochemically induced reductive ring contractions, previously observed for 2,5-dihydro-1,2,4-triazines, have also been verified for 1,4-dihydropyrimidines 2a,b, the dihydro-1,2,4,5-tetrazine 9, and dihydro-1,3,5-triazines 11a,b giving rise to fivemembered fully unsaturated heterocycles (pyrroles 4a,b, imidazoles 13a,b, and triazole 10, respectively). The 1,4-dihydropyrazines 15a-j tend to decompose in acidified 2-propanol in the dark, but on irradiation they also undergo reductive ring contraction furnishing solely the 1,2,5-triarylpyrroles 16a-d rather than the (a priori also possible) isomeric 1,3,4-triarylpyrroles 17a-d. In contrast, the 3,6-diphenylpyrid-azine 18 gives the 4-isopropyl-analogue 19 in low yield upon irradiation in hydrogen chloride saturated 2-propanol. Wiley-VCH Verlag GmbH, 2000.
- Nagy, Jozsef,Madarasz, Zoltan,Rapp, Rudolf,Szoelloesy, Aron,Nyitrai, Jozsef,Doepp, Dietrich
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p. 281 - 290
(2007/10/03)
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- Photochemistry of N-heterocycles, 5: A comparison of chemical and photochemically induced reduction of some 2(4),5-dihydro-1,2,4-triazines and aromatic 1,2,4-triazines
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Chemical reduction (Zn/AcOH) of the arene 1 and of 2(4),5-dihydro-1,2,4- triazine 7 has been reinvestigated, resulting in the amendment of literature data concerning this reaction. Chemical, electrochemical, and photochemically induced reductions and ring contractions of 1,2,4-triazine derivatives have been compared. The first example of a triaryl-1,4-dihydrotriazine has been prepared. Some further evidence is presented that supports the proposed mechanism of the photochemically induced reduction and ring contraction of 1,2,4-triazines.
- Nagy, Jozsef,Horvath, Aniko,Szoelloesy, Aron,Nyitrai, Jozsef
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p. 685 - 689
(2007/10/03)
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- INTERMOLECULAR INTERACTIONS THAT DETERMINE THE REGIOSELECTIVITY IN 1,3-DIPOLAR CYCLOADDITIONS OF N-METHYL-1,3-OXAZOLIUM-5-OLATES WITH N-(PHENYLMETHYLENE)BENZENESULPHONAMIDE
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1,3-Dipolar cycloadditions of N-(phenylmethylene)benzenesulphonamide with mesoionic N-methyl-1,3-oxazolium-5-olates give 2,5-disubstituted imidazole derivatives with high regioselectivity.The intermolecular interactions underlying this regioselectivity we
- Bonati, L.,Ferraccioli, R.,Moro, G.
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p. 452 - 462
(2007/10/02)
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- Synthesis of imidazoles via hetero-cope rearrangements
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A novel synthetic approach to heterocycles containing the imidazole moiety based on the multihetero-Cope rearrangement is described. Oximes are reacted with benzenecarboximidoyl chlorides 4 affording adducts that readily undergo the hetero-Cope rearrangement at slightly elevated temperatures. Acid treatment of the resulting amidines 8 provides imidazoles in very high yields.
- Lantos,Zhang,Shui,Eggleston
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p. 7092 - 7095
(2007/10/02)
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- Cyclometallated compounds of manganese(I) with 1-methylphenylimidazoles
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Cyclometallated complexes of manganese(1) with 1-methylphenylimidazoles have been prepared.IR and 1H NMR spectroscopic studies show they are octahedral complexes in which the imidazole ligand is bound to the metal through the nitrogen and phenyl C(6) atom
- Suarez, Antonio,Vila, Jose Manuel,Pereira, Maria Teresa,Gayoso, Eduardo,Gayoso, Miguel
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p. 359 - 364
(2007/10/02)
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- 4,5-DIPHENYLIMIDAZOLES FROM THE CYCLIZATION OF BENZIL N-ALKYLMONOHYDRAZONES
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The thermal cyclization of monodisubstituted hydrazones (1) affords the corresponding N-substituted-4,5-diphenylimidazoles in good to excellent yields; possible mechanisms for this unusual cyclization are presented.
- Collibee, William L.,Anselme, Jean-Pierre
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p. 655 - 662
(2007/10/02)
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- EFFICIENT PHOTOCHEMICAL OXETANE FORMATION FROM 1-METHYL-2,4,5-TRIPHENYLIMIDAZOLE AND BENZOPHENONES
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In contrast to simple imidazoles, 1-methyl-2,4,5-triphenylimidazole (1) produced stable oxetane photoadducts 3b-e with good efficiency upon irradiation in the presence of benzophenone derivatives 2b-e in acetonitrile solution.Irradiation in the solid-phase was also studied.The oxetanes 3b-e readily underwent cycloreversion by acid catalysis or by heating.
- Ito, Yoshikatsu,Ji-Ben, Meng,Suzuki, Shin,Kusunaga, Yoshitaka,Matsuura, Teruo,Fukuyama, Keiichi
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p. 2093 - 2096
(2007/10/02)
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- THE UNUSUAL CYCLIZATION OF BENZIL MONOHYDRAZONES TO 4,5-DIPHENYLIMIDAZOLES
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Benzil monodisubstituted hydrazones (2) have been shown to undergo cyclodehydration to the corresponding imidazoles (10) and not to pyrazoles as previously reported.
- Collibee, William L.,Anselme, Jean-Pierre
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p. 1595 - 1596
(2007/10/02)
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