Palladium Catalyzed C–I and Vicinal C–H Dual Activation of Diaryliodonium Salts for Diarylation: Synthesis of 4,5-Benzocoumarins

With a strategy that makes use of palladium activation of both C–I and vicinal C–H bonds of diaryliodonium salts, an unprecedented approach in diarylation of coumarins was reported. As such, a wide range of 4,5-benzocoumarins with potential fluorescence properties have been synthesized in good yields. A series of experiments suggested that the formation of two carbon–carbon bonds proceeded in a synergetic manner.