Conversion of 3‑Bromo‑2H‑coumarins to 3‑(Benzofuran-2-yl)‑2H‑coumarins under Palladium Catalysis: Synthesis and Photophysical Properties Study

An intriguing conversion of 3-bromo-2H-coumarins to 3-(benzofuran-2-yl)-2H-coumarins under palladium catalysis is reported. The process involves, from only one single starting material, three transformations and two bond formations in one pot: C–C bond formation via C–H activation and C–O bond formation through 2H-coumarin-to-benzofuran ring contraction under palladium catalysis. Moreover, the photophysical properties of all synthesized compounds were studied.