Liangbin Huang
Wisconsin
The first general cross-Ullman coupling of aryl chlorides with aryl triflates is reported. A bimetallic palladium and nickel catalyst system as well as added lithium chloride is essential to the selective coupling. The reaction conditions tolerate a variety of functional groups on either coupling partner and the utility of the method is illustrated with a three-step syn-thesis of the drug flurbiprofen. The data suggests that the role of LiCl in the reaction is to accelerate catalyst reduction at the zinc surface, which is slow for (dtbbpy)Ni(OTf)2