Expedient Mechanosynthesis of N,N-Dialkyl Imidazoliums and Silver(I)-Carbene Complexes in a Ball-Mill.

The absence of solvent, associated with intensive mechanical agitation, allowed the first mechanosynthesis of high-value silver(I)-carbene complexes and the corresponding N,N-dialkylimidazolium precursors. This procedure gave outstanding results in terms of yield and reaction time, when compared to solution-based conditions previously described in literature, and was generalized to unprecedented compounds. Silver(I)-carbene complexes could either be obtained from N,N-dialkylimidazolium salts or directly from imidazole and alkyl halides in a one-pot two-step procedure without isolating the imidazolium intermediate. Additionally, an efficient one-pot three-step sequence, including imidazole alkylation, silver metalation, and transmetalation is reported.