Mechanochemical Rhodium(III)- and Gold(I)-Catalyzed C-H Bond Alkynylations of Indoles under Solventless Conditions in Mixer Mills.

Mechanochemical activations in RhIII - and AuI -catalyzed C-H alkynylations lead selectively to C2 - and C3 -alkynylated indoles. The processes show excellent functional group tolerance, do not require additional heating and proceed under solventless conditions. Compared to solvent-based standard protocols, the reaction times are shorter and the catalyst quantities lower resulting in high product yields under ambient atmosphere in mixer mills.