Efficient Synthesis of Biaryls through the Kumada Reaction Catalyzed by Carbene Adducts of Cyclopalladated Ferrocenylimine

A series of carbene adducts of cyclopalladated ferrocenylimine were prepared and evaluated in the cross-coupling reaction of aryl halides with Grignard reagents (the Kumada reaction). Complex d exhibited high catalytic activity for the coupling of aryl chlorides with sterically hindered Grignard reagents and the reaction tolerated various functional groups. A wide range of biaryls were efficiently obtained in good to excellent yields in the presence of 0.5 mol-% catalyst under mild reaction conditions.