One-pot synthesis of 1,2,4,5-tetra substituted imidazoles using sulfonic acid functionalized silica (SiO2-Pr-SO3H)

Transition metal-free one-pot synthesis of nitrogen-containing heterocycles

“…Ziarani et al [96] have reported a simple path for the synthesis of fully substituted imidazoles 158 facilitated by acidic silica catalyst from benzils, ammonium acetate, aldehydes, and amines (154, 155, 156, 157) under solvent-free conditions (Scheme 46, Path A). Phosphorus pentoxide supported on silicon dioxide was also utilized as green and reusable catalyst in the synthesis of 1,4,5-tetrasubstituted imidazoles (Scheme 46, Path B) [97].…”

Anticancer Activities of Tetrasubstituted Imidazole‐Pyrimidine‐Sulfonamide Hybrids as Inhibitors of EGFR Mutants

“…While the main four reaction components are well defined, a wide variety of reaction catalysts and conditions have been reported. For example, the readily available and reusable nano-TiCl 4 .SiO 2 , [28] SiO 2 À PrÀ SO 3 H, [29] ZnFe 2 O 4 magnetic nanoparticles, [30] fly ash loaded Bi 2 O 3 À ZnO, [31] zeolite HY and silica gel under microwave irradiation, [32] trityl chloride (TrCl or Ph 3 CCl) under neutral and solvent-free conditions, [33] and Preyssler-type heteropoly-acid catalyst. [34] Interestingly, further methods that utilize fewer than four components have also been reported, such as the photochemical one-pot threecomponent synthesis (from aldehydes, α-aminonitriles, and isoxazoles) of tetrasubstituted imidazoles, [35,36] from amidines and chalcones via FeCl 3 /I 2 -catalyzed aerobic oxidative coupling, [37] sequential reaction of allenyl sulfonamides and amines, [38] from imines, acid chlorides, and N-nosyl imines or ChemMedChem tethered nitriles and mediated by the phosphonitePPh(catechyl) [39] alkylation of synthesized NH imidazoles with alkyl halide.…”

Versatile imidazole synthesis via multicomponent reaction approach

“…The synthesis of 2,4,5‐trisubstituted imidazoles are normally carried out by the reaction of 1,2‐diketone, α ‐hydroxy/silyloxyketone/acetoxy, or 1,2‐ketomonoxime with an CH 3 COONH 4 (Ammonium acetate) and Aldehyde (Route I in Figure 4A) in different reaction condition like using simply HOAc [ 53–55 ] or solid supported acids, [ 56–63 ] ionic liquids, [ 64, 65 ] under microwave [ 66 ] or ultrasonic [ 67 ] irradiation, under conventional method of central heating in the existence of metal catalytic agent [ 68–74 ] or by the help of solar heating condition, [ 75 ] (b) in the presence of various Lewis acid catalysts (Route II), [ 76 ] (c) Ni‐catalyzed cyclotrimerization of aromatic nitriles (under pressure range of not <60 and not more than 120 psi and high level of temperature which approximately ranges from 180–230°C) hydrogenation condition aimed at long (48 h) (refer Route III in scheme I) [ 67 ] ; or Pd‐catalyzed one single phase synthesis from imine and chlorides of acids via the formation of Münchnones (Route IV, Figure 4A). [ 68–79 ] The 1,2,4,5‐tetrasubstituted compounds of imidazoles formation involve a reaction of a 1,2‐diketone, α ‐acetoxy/hydroxy/silyloxyketone, or 1,2‐ketomonoxime, an aldehyde (‐CHO), an amine and CH 3 COONH 4 (Ammonium acetate) (refer Route V of Figure 4B).…”

“…Mohammadi Ziarani et al synthesized 1,2,4,5‐tetrahedrally‐substituted imidazoles by reacting benzil, aromatic aldehydes, and ammonium acetate in the presence of water as the solvent for about 10 min with yield ranging from 85 to 98%, as depicted in Figure 5A. [ 56 ] Mekheimer et al also suggested a reaction actively involved in preparing tetrasubstituted imidazole by using high surface area SiO 2 as a catalyst. The reaction was induced by solar thermal energy.…”