Palladium-Catalyzed Decarbonylative Borylation of Benzylic Acids for the Synthesis of Benzylboronates

A palladium-catalyzed decarbonylative borylation of benzylic carboxylic acids by selective C-O cleavage is reported. A variety of benzylic acids bearing different functional groups are well tolerated by this method. The reaction accomplishes the synthesis of valuable pinacol benzylboronates from common benzylic acids by net decarbonylation. The key steps involve oxidative addition to the acyl C(O)-O bond and selective CO extrusion. This general and practical approach is expected to be widely applied to the synthesis of diverse benzylic boronic esters.