Mechanochemical Ruthenium-Catalyzed Hydroarylations of Alkynes under Ball-Milling Conditions.

Under solventless grinding conditions, mechanochemical ruthenium-catalyzed hydroarylations of alkynes with acetanilides lead to trisubstituted alkenes. Only catalytic amounts of pivalic acid or copper acetate are required, and without the need for external heating, the reaction times are shorter than those of their solution-based counterpart. Mechanochemical oxidative annulations through palladium-catalyzed intramolecular amination convert the products into N-acetylindoles.