Benzimidazole ionic liquids reactions

Benzimidazoles possess important pharmacological activities such as antimicrobial, antifungal, antiparkinson, anticancer, and antibiotic. The one-pot regioselec-tive synthesis of these compounds has been performed by taking a heteroaromatic amine and/or 1,2-phenylenediamine with 2-mercaptoacetic acid and an aromatic aldehyde in ionic liquids, namely, l-butyl-3-methylimidazolium trifluoroborate ([bmim][BF ]) and l-methoxyethyl-3-methylimidazolium trifluoroacetate ([MOEMIM][TFA]). The reaction has been carried out under nitrogen atmosphere (Figs. 12.7, 12.8) [6]. Consideration of the yields of compounds revealed that [MOEMIM][TFA] is a better reaction media in comparison to [bmim][BF ]. 

Ionic liquids have been reported to accelerate slow AT-benzylation reactions of benzimidazole 65 utilizing dibenzyl carbonate 66 as an alkylating reagent (Scheme 13) [55]. An additional rate enhancement was observed when microwave irradiation was applied in this reaction to afford the N-benzylbenzimidazole 67. 

Saha, D., Saha, A., and Ranu, B. C. (2009). Remarkable influence of substituent in ionic, liquid in control of reaction simple, efficient and hazardous organic solvent free procedure for the synthesis of 2-aryl benzimidazoles promoted by ionic Uquid, [pmim]BF4. Green Chem., 11, 733 737. 

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