Chlorotropy of 1-Chlorobenzimidazole

Abstract

The chlorotropy observed by NMR in this study occurred by the rapid intermolecular transfer of a chloro group between 1-chlorobenzimidazole and benzimidazole in CCl4/CH3OH/K2CO3 solution.

Diels–Alder Reaction in the Synthesis of Fluorinated (Hetero)Aromatic Compounds

“…[45] Similarly, the reaction with 1-substituted 2-aminopyrroles gave the pyrrolo[2,3-d]pyrimidines 110, [46] while with 3-aminopyrrole (generated from 3-nitropyrrole) pyrrolo[3,2-d]pyrimidine 111 was obtained. [47] Furthermore, the reaction of 107a with 2-aminoindoles lead to 9H-pyrimido[4,5-b]indoles 112. [48] Similarly, the reactions of triazines 107a,b with 2-amino-3thiophene-and 3-amino-2-thiophene carboxylates gave thieno[2,3-d]pyrimidines 113a,b and thieno[3,2-d]pyrimidine 114a (from 107a), respectively in moderate yields (Scheme 41).…”

“…Fused heterocycles 108-112 obtained by IEDDA reactions of triazines 107a,b with corresponding aminoazoles. [44][45][46][47][48] Scheme 42. Synthesis of pyrimidines 115 from triazine 107a.…”

Nuclear Quadrupole Resonance Spectroscopy: Tautomerism and Structure of Functional Azoles

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The Nuclear Quadrupole Resonance spectroscopy data of functionalized azoles (imidazoles, triazoles and corresponding benzazoles) are reviewed and critically discussed. The possibility of studying the tautomerism of azoles by the NQR method is considered.Crystals 2019, 9, 366 2 of 12 transfer of a chlorine atom between 1-chlorobenzimidazole and benzimidazole in a CCl 4 /CH 3 OH/K 2 CO 3 medium [52,53]. A similar chlorotropic rearrangement was observed in the equilibrium exchange process between 1-chloroindole and 3-chloro-3H-indole, i.e., the fast intermolecular transformations of 1-chloroindole to 3-chloroindole in the related media were detected [53].

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“…Crystals 2019, 9, 366 2 of 12 transfer of a chlorine atom between 1-chlorobenzimidazole and benzimidazole in a CCl 4 /CH 3 OH/K 2 CO 3 medium [52,53]. A similar chlorotropic rearrangement was observed in the equilibrium exchange process between 1-chloroindole and 3-chloro-3H-indole, i.e., the fast intermolecular transformations of 1-chloroindole to 3-chloroindole in the related media were detected [53].…”

“…The intensive subsequent NMR [46,50], and NQR [46], studies evidenced that the compound turned out to be symmetrical 2-chloro-4,5-diphenyl-1,2,3-triazole5,6-dichloro-4,7-dimethylbenzotriazole. Some examples of chlorotropic transformations in other azoles are also known [52,53]. The chlorotropic exchange in 1-chlorobenzimidazole revealed by NMR spectroscopy is due to the rapid intermolecular chlorobenzimidazole revealed by NMR spectroscopy is due to the rapid intermolecular transfer of a chlorine atom between 1-chlorobenzimidazole and benzimidazole in a CCl4/CH3OH/K2CO3 medium [52,53].…”