Palladium-catalyzed carbon�nitrogen bond formation is an important technology that is highly-utilized by practitioners of synthetic chemistry. Our group, among many others, has been deeply involved in the development of catalytic methods that achieve the cross-coupling of carbon-based electrophiles (such as aryl halides or pseudohalides) with nitrogen-based nucleophiles (including amines or amides). We recently questioned whether multiple C�N coupling reactions could be conducted in cascade, specifically where two different nitrogen-based nucleophiles could react with two discrete carbon-based electrophiles in a selective fashion using the same catalyst to mediate both transformations. This presentation describes the successful realization of this strategy wherein 1,2-dihalobenzene substrates are coupled with both amine nucleophiles and amide nucleophiles to afford a wide range of complex benzimidazole products. Furthermore, substituted 1,2-dihalobenzene substrates readily participate in this process to give the corresponding benzimidazole products with complete regioselectivity. Given the importance of benzimidazoles to the pharmaceutical, agrochemical and functional materials industries, we are confident that the described method will be of general interest and value to synthetic chemists working in these and related research areas.

Novel synthesis of benzimidazoles via cascade palladium catalysis

245th National Meeting (2013)

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