Selective Synthesis of Trisubstituted Imidazoles by Iodine‐Catalyzed [3+2] Cycloadditions

Abstract

In this paper, two novel and efficient methods for the synthesis of trisubstituted imidazoles have been developed through iodine-catalyzed [3 + 2] cycloaddition. By controlling one of the reaction materials, we selectively synthesized 1,2,4-trisubstituted imidazoles and 1,2,5-trisubstituted imidazoles. The desired products were obtained in moderate to good yields with wide functional groups compatibility under standard conditions.

Iodine-Catalyzed Cascade Annulation of 4-Hydroxycoumarins with Aurones: Access to Spirocyclic Benzofuran–Furocoumarins

“…It is widely available, inexpensive, nontoxic, eco-friendly, and moisture resistant, and employed as a catalyst, resulting in the formation of new C-C [32,33], C-N [34,35], C-O [36], and C-S [37,38] bonds. In addition, molecular iodine has been recognized as a powerful tool for constructing the pharmacologically important heterocyclic rings [39][40][41]. Currently, several approaches have also been disclosed for the synthesis of spiro-heterocycles through iodine-mediated cascade reactions [42][43][44].…”

GO‐TiO2 Nanocomposite: An Efficient Catalyst for the Conventional and Ultrasonically Mediated Multicomponent Synthesis of 2, 4, 5‐Trisubstituted Imidazole Derivatives**

“…[15] Use of various catalysts for the synthesis of imidazole derivatives is also well depicted in the literature. For example, large scale of catalysts like H 14 [NaP5W30O110], [16] Zr(acac) 4 , [17] Lproline, [18] Y(TFA) 3 , [19] PEG-400, [20] DABCO, [21] Cu(TFA) 2 , [22] MoO 3 / SiO 2 , [23] silica sulfuric acid, [24] SbCl 3 /SiO 2 , [25] heteropolyacids, [26] NBS, [27] Cu(OTf) 2 -/I 2 , [28] ZrCl 4 , [29] Sulfated Polyborate, [30] iodine, [31] Er(OTf) 3 , [32] scolecite, [33] ZnO nanorods, [34] MgO NPs, [35] Cofe 2 O 4, [36] geopolymer-Nife 2 O 4 nanocomposite, [37] nano-Al 2 O 3, [38] NH 4 OAc/ PivOH, [39] NiO NPs, [40] Polymer-supported zinc chlorides, [41] Yb-(OTf) 3, [42] γ-Fe 2 O 3 @TiO 2 -EG-Cu(II) [43] and CuI [44] have been employed for the imidazole synthesis and they have their own advantages. However, many of the reported synthetic methods suffer with some limitations like complicated reaction conditions, expensive chemicals, low atom economy, tedious work up and the use of strong oxidants.…”

Electrochemical multicomponent [2+2+1] cascade cyclization of enaminones and primary amines towards the synthesis of 4-acylimidazoles

“…32 In 2021, iodine-catalyzed [3+2] cycloadditions of amidines with propiophenone were developed to synthesize polysubstituted acylimidazoles by Huang's group (Scheme 1c). 33 However, these approaches usually suffer from a multi-step reaction, addition of an oxidant, and high temperature. Thus, the development of efficient and green methods for constructing acylimidazole-containing compounds remains of great significance.…”