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.