American Chemical Society
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Copper-Catalyzed Synthesis of Benzimidazoles via Cascade Reactions of o-Haloacetanilide Derivatives with Amidine Hydrochlorides

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journal contribution
posted on 2008-10-03, 00:00 authored by Daoshan Yang, Hua Fu, Liming Hu, Yuyang Jiang, Yufen Zhao
We have developed an efficient method for the synthesis of benzimidazoles via cascade reactions of o-haloacetoanilide derivatives with amidine hydrochlorides. The protocol uses 10 mol % CuBr as the catalyst, Cs2CO3 as the base, and DMSO as the solvent, and no ligand is required. The procedure proceeds via the sequential coupling of o-haloacetoanilide derivatives with amidines, hydrolysis of the intermediates (amides), and intramolecular cyclization with the loss of NH3 to give 2-substituted 1H-benzimidazoles.