One-Pot Synthesis of Polysubstituted Imidazoles From Arylaldehydes in Water Catalyzed by NHC Using Microwave Irradiation

Abstract

A simple, high yielding synthesis of tri (3a-i) and tetrasubstituted (4a-g) imidazols from aldehydes is described. The cornerstone of this methodology involves the condensation of NH 4 OAc, substituted aldehydes, and benzoin, which is synthesized in situ from aldehydes catalyzed by N-heterocyclic carbine (NHC), under microwave irradiation in water to afford trisubstituted imidazoles (3a-i). If arylamine is added in the solution, tetrasubstituted imidazoles (4a-g) can be obtained. Lepidilines B and trifenagrel are also synthesized in high yield using this procedure. All the experiment deta are in agreement with the literature.

A Facile and Green Approach for the One‐Pot Multicomponent Synthesis of 2,4,5‐Triaryl‐ and 1,2,4,5‐Tetraarylimidazoles by Using Zinc‐Proline Hybrid Material as a Catalyst

“…Similarly for the synthesis of 1,2,4,5‐tetraarylimidazole, benzil or benzoin (1mmol), appropriate aldehyde (1mmol), appropriate amine (1mmol) and ammonium acetate (1mmol) were taken in 10 ml of Water: ethanol (4:1) mixture and rest protocol is same. Unambiguously the structures of the products were established on the basis of their spectral analysis (IR, 1 H‐NMR, 13 C‐NMR data, LC‐MS data) ,,,…”

Benefits and applications of microwave-assisted synthesis of nitrogen containing heterocycles in medicinal chemistry

“…In order to diversify the imidazole center, the synthesis of polyaromatic imidazoles bearing different substituents on aryl 62 The following methodology afforded trisubstituted imidazoles bearing chloro, bromo or methyl groups on the phenyl ring in good yields, while their furanyl, pyridinyl, nitro and hydroxyl phenyl correspondences could not be obtained.…”

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.…”