Metal-Catalyzed Thermal Reactions of Cyclic β‑Dicarbonyl Phenyliodonium Ylide with Styrenes

A cyclic β-dicarbonyl phenyliodonium ylide reacted with various substituted styrenes under Rh<sub>2</sub>(OAc)<sub>4</sub> catalysis to give cyclopropanes and dihydrofurans in a highly regioselective fashion. When styrenes with electron-donating substituents or disubstituted were employed, only dihydrofurans were isolated instead. A mechanism involving two competing pathways rationalizes the results.