Palladium-bisimidazol-2-ylidene complexes as catalysts for general and efficient Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids

A series of bisimidazolium salts 1–6 were synthesized and evaluated as precursors to bisimidazol-2-ylidene ligands in palladium-catalyzed Suzuki cross-coupling reactions with aryl chlorides and arylboronic acids. The bisimidazolium salt 6 was found to be superior over imidazolium and other bisimidazolium salts affording high yields of biaryl products employing a wide variety of substrates.