Lithiation and Alkylation of the Imidazole Backbone

Abstract A concise improved method for the alkylation of the imidazole backbone has been developed. The positions 1 and 2 of the imidazole ring were protected with tetrahydro‐2 H ‐pyran‐2‐yl and chloro groups, respectively. Position 5 of imidazole was then lithiated, whereupon alkylation could be conducted by means of a variety of electrophilic reagents including haloalkanes, aldehydes, and ketones. Finally, the two protective / auxiliary groups on the positions 1 and 2 were easily removed by means of treatment with acid and base and hydrogenation, respectively. The developed method proved good functional group tolerance but demanded non‐bulky molecular moieties in the vicinity of the attaching C‐atom of the reagent. The novel alkylating method was used to synthesize two new NHC−Ag complexes holding branched alkyl groups on the imidazole backbone.