Metal-Catalyzed Cascade Rearrangements of 3‑Alkynyl Flavone Ethers

Metal-mediated rearrangements of 3-alkynyl flavone ethers are reported. The overall process involves 5-endo enyne cyclization to a platinum-containing spiro-oxocarbenium intermediate which may be trapped with methanol to produce spirodihydrofurans or further rearranged to afford either allenyl chromanediones or benzofuranones.