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

A cyclic beta-dicarbonyl phenyliodonium ylide reacted with various substituted styrenes under Rh-2(OAc)(4) 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.