Studies on the Cocatalyst in Ruthenium-Catalyzed C–H Arylation

The performance of three types of Brønsted acid potassium salts, potassium carboxylates, potassium phosphates, and potassium sulfonates, has been tested as the cocatalyst in ruthenium-catalyzed C–H arylation. Among them, dipotassium glutarate, potassium bis(2-ethylhexyl) phosphate, and potassium 2,4,6-trimethylbenzenesulfonate provided higher activity. Potassium 2,4,6-trimethylbenzenesulfonate was the most active even for less reactive substrates, such as electron-deficient azoles and sterically demanding aryl bromides.