One-pot synthesis of highly substituted imidazoles using molecular iodine: A versatile catalyst

One-pot synthesis of 2,4,5-trisubstituted imidazole derivatives catalyzed by btppc under solvent-free conditions

“…Intermediate [I], in the presence of BTPPC, condenses with benzyl or benzoin to form intermediate [II], which in turn rearranges to the trisubstituted imidazole by a hydrogen shift [1,5]. In summary, a one-pot, multicomponent methodology has been developed for the synthesis of lophine derivatives catalyzed by BTPPC in high yields.…”

“…Several methods such as the hetero-Cope rearrangement [3] and four-component condensation [4] for the synthesis of trisubstituted imidazoles are reported. In recent years, the synthesis of 2,4,5-trisubstituted imidazoles has been catalyzed by I 2 [5], ZrCl 4 [6], ionic liquid [7], L-proline [8], microwave irradiation [9], Yb(OPf) 3 [10] [18], N-methyl-2-pyrrolidone hydrogen sulfate [19], europium triflate [20], sulfated zirconia [21], n-Bu 4 NBr [22], silica-supported Preyssler nanoparticles [23], (NH 4 ) 6 Mo 7 O 24 ⋅4H 2 O [24], nano MgO [25], nano aluminium nitride [26], nano SiO 2 -supported ferric hydrogen sulfate (FHS) [27] and KSF supported 10-molybdo-2-vanadophosphoric acid [28]. Although some of the methods are actually efficient from the synthetic chemist's points, many of the synthetic protocols for imidazoles reported above suffer from one or more disadvantages, such as harsh reaction conditions, poor yields, and prolonged reaction time, use of hazardous and often expensive acid catalysts.…”

Environmentally Benign Synthesis of Tetra-Substituted Imidazoles through 4-Components Strategy Mediated by (<I>S</I>)-3-Methyl-1, 1-Diphenylbutane-1, 2-Diamine

“…A lot of synthetic routes are available in the literatures to synthesize imidazoles [11] analogues including annulations of amidines and β-keto esters [12], SBA-Pr-SO 3 H [13], nanocrystalline MgAl 2 O 4 [14], Cellulose/ɤ-Fe 2 O 3 /Ag [15], urea/hydrogen peroxide (UHP) [16], N-acetyl glycine (NAG) [17] [27], 2-cyanopyridine [28], p-TsOH [29], cellulose sulfuric acid [30], ceric (iv) ammonium nitrate (CAN) [31], boric acid [32], PEG-400 [33] [43], eutectic solvents [44], iodine [45], Yb(OTf) 3 [46], ZrCl 4 [47], AcOH [48], disubstituted alkynes [49] are noteworthy. However, almost all of these methods suffer from one or more constraints such as lower yield, harsh reaction conditions, tiresome isolation technique, uses of expensive toxic metal catalysts, limited examples etc.…”

Nano Copper Ferrite Catalyzed Sonochemical, One-Pot Three and Four Component Synthesis of Poly Substituted Imidazoles

“…In the same way several methods have been reported for the synthesis of tetra substituted imidazoles by cyclo condensation of 1,2 dicarbonyl compounds, various aromatic aldehydes, ammonium acetate and aromatic/aliphatic amines using various catalysts such as nano TiCl 4 •SiO 2 [26] [33] as catalyst under Ultra sound irradiation. In extension with these procedures, several methods have been reported for the synthesis of both tri and tetra substituted imidazoels using various catalysts such as molecular Iodine [34], Sodium dihydrogen phosphate [35], BiCl 3 [36], DABCO [37] According to the literature survey, several synthetic protocols have been reported for the synthesis of substituted imidazoles using various type of copper containing catalyst such as synthesis of imidazoles through the Cu 2 O catalyzed cross-cycloaddition between two different isocyanides [43], Synthesis of 1,2,4-trisubstituted imidazoles through the CuCl 2 -catalyzed oxidative diamination of terminal alkynes by amidines [44], Synthesis of multi substituted imidazoles via CuI-catalyzed [3 + 2] cycloadditions [45]. The above reported methods have its own importance and merits, however most of these methods require harmful catalysts, and difficult work-up and effluent pollution.…”