Barium Chloride (Bacl2): a Mild and Efficient Catalyst for the Synthesis of Benzimidazoles and Its Derivatives Under Microwave Irradiation

Archive of SID

17th Iranian Chemistry Congress Vali-e-Asr University of Rafsanjan 1-3 september 2014

Barium Chloride (BaCl2): A Mild and Efficient Catalyst for the Synthesis of Benzimidazoles and its Derivatives Under Microwave Irradiation

Masumeh Abdoli-Senejani,a Atefeh Saberi,b,*

a Department of Chemistry, Islamic Azad University-Arak Branch, Arak, Iran; [email protected]; [email protected] b Department of Chemistry, Islamic Azad University-Arak Branch, Arak, Iran; [email protected] Background: Molecules having benzimidazole as a basic structural unit is known to exhibit a wide range of biological properties [1, 2]. The potency and wide applicability of imidazol pharmacophore can be attributed to its hydrogen bond donor/acceptor capability as well as its high affinity for metals, which are present in many protein active sites [3, 4]. Benzimidazoles contains a bicyclic system in which benzene has been fused to the 4 and 5 position of the hetero cycle (imidazole). By knowing the advantages of microwave reaction [5], we felt that the synthesis of the various benzimadazoles under microwave irradiation using barium chloride.

Methods: A mixture of ortho-phenylenediamine and benzaldehyde in the presence of barium chloride in methanol was stirred at room tempereture. The progress of the reaction was monitored by thin layer chromatography (TLC).

NH O 2 N BaCl2 + R R H CH OH NH 3 N 2 H

Results: This method allows us to obtain excellent yields of required product in shorter reaction times as compared to those of classical methods.

Conclusion: In conclusion, the catalyst barium chloride has been demonstrated as a novel and efficient promoter for the synthesis of benzimidazoles in high yields, from ortho-phenylenediamine and a wide variety of aldehydes. Microwave irradiated synthesis of benzimidazoles was carried out to get higher yield with less reaction time period as compared to conventional method.

Keywords: Benzimidazole; Synthesis; O-phenylenediamine; barium chloride; microwave irradiation.

References

[1] Sondhi, S.M.; Singhal, N.; Johar, M.; Reddy, B.S.N.; Lown, J.W. Curr. Med. Chem. 2002, 1045. [2] Horton, D.A.; Bourne, G.T.; Smythe, M.L. Chem. Rev. 2003, 893. [3] Haul, N.H.; Nar, H.; Priepke, H.; Ries, U.; Stassen, J.;Wienen, W. J. Med. Chem. 2002, 45, 1757. [4] Nakano, H.; Inoue, T.; Kawasaki, N.; Miyataka, H.; Matsumoto, H.; Taguchi, T.; Inagaki, N.; Nagai, H.; Satoh, T. Bioorg. Med. Chem. 2000, 373. [5] Jubie, S. et al, J. Pharma. Sci. & Res. 2010, l2 (2), 69.

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