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.

A facile and efficient method was described for oxidation of some 3,5-diacyl or 3,5-diester 1,4-dihydropyridines using H 2 O 2 in the presence of superparamagnetic core-shell metal-organic framework Fe 3 O 4 @Ni-MOF. The Fe 3 O 4 @Ni-MOF has been obtained byStep-by-Step method in which magnetic Fe 3 O 4 magnetic nanoparticles were coated with Ni-MOF using a mercaptoacetic acid linker. The synthesized catalyst was characterized using thermogravimetric analysis, FT-IR spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy and energy-dispersive X-ray analysis. The novel superparamagnetic core-shell metal-organic framework Fe 3 O 4 @Ni-MOF revealed high efficiency for oxidation of various 1,4-dihydropyridines using hydrogen peroxide. The Box-Behnken design matrix and the response surface method were applied to investigate the optimization of the reaction conditions. The conditions for optimal reaction yield and time were: amount of catalyst ≈17 mmol, temperature ≈78 C and amount of hydrogen peroxide ≈ 1 ml. A variety of 3,5-diacyl or 3,5-diester 1,4-dihydropyridines with different substituted functional groups have been converted to corresponding pyridines with good to excellent isolated yields using H 2 O 2 and Fe 3 O 4 @Ni-MOF. The catalyst was reused up to five times for the oxidation of 1,4-dihydropyridines without a significant loss in catalytic activity. The short reaction times, simplicity of method, good to excellent yields and reusability of catalyst were some advantages of the proposed procedure.