An Efficient Synthesis of Benzimidazole and Benzothiazole Derivatives Using a Nickel(II) Metal-Organic Framework

Abstract

Background: The benzimidazoles and benzothiazoles have shown relatively high pharmaceutical and biological activities. In recent years, numerous methods have been developed for synthesis of benzimidazole and benzothiazole derivatives using different catalysts. However, only some of the reported procedures are quite satisfactory and most of them have drawbacks. Herein, we report a convenient method for synthesis of benzimidazole and benzothiazole derivatives using a nickel (II) metal-organic framework (Ni- MOF) as a novel and reusable catalyst. The presence of unsaturated metal centers makes metal-organic frameworks to be used as Lewis acid catalysts. Objective: The primary objective of this study was to describe an efficient method for synthesis of benzimidazole and benzothiazole derivatives. Methods: Ni-MOF was prepared using the modified evaporation method and was characterized by FE-SEM, FT-IR, TGA, and XRD techniques.The catalyst was then used to test the synthesis of some benzimidazole and benzothiazole derivatives. The benzimidazoles and benzothiazoles were characterized by Elemental analyses, HNMR and IR techniques. Results: A variety of aromatic aldehydes bearing electron donating groups or electron-withdrawing were reacted with 1,2-phenylenediamine or 2-aminothiophenol using Ni-MOF in good to excellent yields. Conclusion: In summary, a new and highly efficient method was developed and reported for the synthesis of benzimidazole and benzothiazole derivatives using nickel(II) metal-organic framework. The advantages are short reaction times, good to excellent yields, the environmentally benign and simple procedure, stability, nontoxicity, recyclability, and easy separation of the catalyst.

Superparamagnetic core‐shell metal–organic framework Fe3O4@Ni‐MOF as efficient catalyst for oxidation of 1,4‐dihydropyridines using hydrogen peroxide

“…[44] The other bands, 1142 and 1298 (stretching vibration of SO 2 ), 1498 and 1623 (aromatic C=C), 1594 (bending vibration of N-H) confirmed the presence Ni-MOF. [39] In order to study thermal stability of the synthesized Fe in Figure 3. The initial weight loss of 2.71% from 30.66 C to 108.16 C was observed resulting from the loss of adsorbed water.…”

“…[36][37][38] 2 | RESULTS AND DISCUSSION Recently, we have been using Nickel (II) MOF (Ni-MOF) as a new and effective catalyst for the preparation of 2-aryl benzimidazole and benzothiazole derivatives. [39] In continuation of our research to develop efficient and green methods for the synthesis of heterocyclic compounds, [40][41][42] here, we describe a facile and convenient procedure for the oxidation of 3,5-diacyl or 3,5-diester 1,4-dihydropyridines using H 2 O 2 in the presence of Fe 3 O 4 @Ni-MOF as a catalyst (Scheme 1).…”

“…Furthermore, additional peaks agree with the XRD pattern of Ni-MOF. [39] Figure 2 shows the FT-IR spectra of Fe 3 O 4 , Ni-MOF and Fe 3 O 4 @Ni-MOF. The relatively strong adsorption peak at 560 cm À1 could be attributed to the Fe-O stretching vibration of Fe 3 O 4 , indicating the existence of Fe 3 O 4 in the catalyst.…”

“…[44] The other bands, 1142 and 1298 (stretching vibration of SO 2 ), 1498 and 1623 (aromatic C=C), 1594 (bending vibration of N-H) confirmed the presence Ni-MOF. [39] In order to study thermal stability of the synthesized Fe 3 O 4 @Ni-MOF, TGA of Fe 3 O 4 @Ni-MOF under a nitrogen atmosphere from room temperature to 800 C is given…”