One-pot synthesis of substituted imidazole derivatives by a new designed BiFeO₃/CuWO₄ heterojunction nanocatalyst

Abstract

Development of new multicomponent reactions (MCRS) is an area of considerable interest due to the fact that the products are formed in a single step and also the variety could be achieved only by changing the reaction components. Imidazole derivatives are in a very interesting class of heterocyclic compounds, because they have many pharmacological properties and play important roles in biological processes. The imidazole compounds are known to possess NO synthase inhibition and antifungal, antimycotic, antitumor, antibiotic, antibacterial, antiulcerative, and CB1 receptor antagonistic activities. Various substituted imidazoles act as B-Raf kinase, glucagon receptors, inhibitors of p38 MAP kinase, plant grown regulators, therapeutic agents, and pesticides [1,2]. These propellants have engendered considerable interest among synthetic organic and medicinal chemists in recent years. Accordingly, a number of synthetic methods have been reported for the synthesis of 2,4,5-trisubstituted imidazoles. These methods involve condensation of benzil or benzoin, aryl aldehydes and ammonium acetate by using various catalytic systems [3]. But, some of these synthetic methods are associated with one or more drawbacks such as using expensive reagents, long reaction times, purifications, complex work-up, generation of large amount of toxic wastes, strongly acidic conditions, high temperature, poor yields and occurrence of side reactions [4,5]. Owing to the wide range of pharmacological and biological activities, the development of effective, high yielding, economical, clean and mild environmental benign protocols is still desirable and is in demand. Moreover, the design of valuable, effective and recoverable catalysts is important for the both environmental and economic point of view. Owing to the wide range of pharmacological and biological activities, the development of effective, high yielding, economical, clean and mild environmental benign protocols is still desirable and is in demand. Moreover, the design of valuable, effective and recoverable catalysts is important for the both environmental and economic point of view. Herein we wish to report a new efficient and practical route for the synthesis of trisubstituted imidazoles by the condensation reaction of benzil or benzoin, aryl aldehydes and ammonium acetate catalyzed by novel BiFeO₃/CuWO₄ heterojunction nanoparticles. To the best of our knowledge, this is the first report of design, preparation, and characterization of BiFeO₃/CuWO₄ heterojunction and its application as a heterogeneous catalyst in organic reactions. This novel approach has several superiorities as compared with the previous reports for the synthesis of substituted imidazole derivatives and opens an important area to the use of environmentally benign and recoverable heterogeneous nanocatalyst in the synthesis of pharmaceutically important heterocyclic compounds.

References 

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[2] D. Kumar, D. N. Kommi, N. Bollineni, A. R. Patel and A. K. Chakraborti, Green Chem., 2012, 14, 2038.

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[4] D. I. MaGee, M. Bahramnejad and M. Dabiri, Tetrahedron Lett., 2013, 54, 2591.

[5] A. Keivanloo1, M. Bakherad, E. Imanifar and M.Mirzaee, Appl. Catal., A, 2013, 467, 291.