Base-Free Palladium-Catalyzed Hydrodechlorination of Aryl Chlorides with Pinacol Borane

Base-free palladium-catalyzed reactions of aryl chlorides with pinacol borane have been found to give the hydrodechlorinated products while similar reactions of aryl halides with pinacol borane in the presence of a base were reported to result in borylation. The base-free conditions offer reasonable functional group compatibility. Experimental studies suggest that smooth and selective hydride transfer from pinacol borane to arylpalladium chloride under base-free conditions is promoted by a strong interaction between the Lewis acidic boron and the chlorine on the palladium.