Umpolung Direct Arylation Reactions: Facile Process Requiring Only Catalytic Palladium and Substoichiometric Amount of Silver Salts

An umpolung direct arylation process is described. The reaction requires only a catalytic amount of Pd(OAc)(2) and a substoichiometric amount of silver salts, without any external base or ligand to proceed. The directed oxidative insertion of the transition metal followed by the coupling into the C-H bond of an unactivated arene has surprisingly not yet been reported, despite the clear advantages in the ease of starting material synthesis. The reaction is regioselective with regards to the arene partner, and the role of the acetate and carbonate groups has been elucidated. This methodology adds to the very few examples of benzene coupling without the inclusion of electron-withdrawing groups to increase acidity.