An Efficient Synthesis of 2,4,5‐Trisubstituted and 1,2,4,5‐Tetrasubstituted Imidazoles Using Dihydroquinolines as Novel Organocatalyst

Abstract

A simple, and environmentally benign synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles has been successfully accomplished via multi‐component cyclo‐condensation of 1,2‐dicarbonyl, aldehyde, and ammonium acetate and aniline respectively, using dihydroquinoline based novel organocatalysts at refluxed temperature in ethanol. High yields (94 %), easy work‐up and purification of products without column chromatography are the key advantages of the method.

An efficient multicomponent synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by a magnetic nanoparticle supported Lewis acidic deep eutectic solvent

“…[18][19][20] Imidazoles are important bioactive heterocyclic compounds which have been proved to possess antitumor, antibacterial, fungicides, herbicides, plant growth regulators, antiviral activities. [21][22][23][24] Various protocols for preparation of imidazoles via multicomponent reaction have been tested in literature, which employs a three-component reaction of 1,2-diketone or ketomonoxime, aldehyde, and ammonium acetate, or four-component reaction of 1,2-diketone, aldehyde, primary amines, and ammonium acetate. [25][26][27][28] Many of the synthetic approaches for the preparation of imidazoles suffer from one or more drawbacks such as drastic reaction conditions, low yields, by-products, prolonged reaction time, volatile organic solvent, tedious work-up processes, expensive and unrecyclable catalysts.…”

A green and practical one‐pot two‐step strategy for the synthesis of symmetric 3,6‐diarylpyridazines

“…Nowadays, one‐pot multicomponent reactions (MCRs) are very useful in organic synthesis, drug, and drug‐like molecular discovery owing to their simplicity, flexibility, and efficiency compared with a conventional multistep linear synthetic strategy …”

Novel and Reusable Mesoporous Silica Supported 4-Methylbenzenesul- fonate-functionalized Ionic Liquids for Room Temperature Highly Efficient Preparation of 2,4,5-Triaryl-1H-imidazoles

“…When the structure of substitute containing electron withdrawing groups, it took longer time of 1 h to satisfy the excellent yields (Table 2, entries 6-10). Based on the above experimental results and related literature methods [15][16][17][18][19][20], a possible synergetic catalytic mechanism for the synthesis of 2,4,5-triaryl-1H-imidazoles over Ti-SBA-15@ILTsO was proposed and presumed in Scheme 3. Firstly, benzyl was activated by the Ti sites of support through the polarization, and after that the nucleophilic attack of N atom led by NH4OAc for making the intermediate A.…”

“…However, these methods often suffered from low yields, harsh conditions, and tedious procedures. Over the past decades, a large number of catalysts have been reported for the synthesis of 2,4,5-triaryl-1H-imidazoles such as molecularly imprinted polymer [8], iodine/DMSO [9], NiO nanocomposites/rGO [10], Fe 3 O 4 @SiO 2 •HM•SO 3 H [11], Co complex@KCC-1 [12], CSNPs/MWCNT@Fe 3 O 4 [13], CAN [14], Fe 3 O 4 @CS [15], dihydroquinoline [16], LADES@MNP [17], and others [18][19][20]. Unfortunately, most of these protocols still suffered from disadvantages such as the stoichiometric use of catalysts, high reaction temperatures, tedious isolation techniques, and catalyst recycle problems.…”