Copper-catalysed C-H functionalisation gives access to 2-aminobenzimidazoles

Clark, Peter R. and Williams, Glynn D. and Tomkinson, Nicholas C. O. (2019) Copper-catalysed C-H functionalisation gives access to 2-aminobenzimidazoles. Organic and Biomolecular Chemistry, 17 (34). pp. 7943-7955. ISSN 1477-0520

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    This paper describes the development, optimisation and exemplification of a copper-catalysed C–H functionalisation to form pharmaceutically relevant 2-aminobenzimidazoles from aryl-guanidines. High throughput screening was used as a tool to identify a catalytically active copper source, DoE was used for reaction optimisation and a range of aryl-guanidines were prepared and exposed to the optimum conditions to afford a range of 2-aminobenzimidazoles in moderate to good yields. The methodology has been applied to the synthesis of Emedastine, a marketed anti-histamine pharmaceutical compound, with the key cyclisation step performed on a gram-scale.