Synthesis of spirocyclopropanes via iodine-promoted bimolecular cyclization of 2-benzylidene 1,3-indandiones

A novel and efficient iodine-promoted bimolecular annulation of 2-benzylidene 1,3-indandiones has been developed. Following this protocol, a series of spirocyclopropane derivatives were furnished in good to excellent yields. The present protocol features mild conditions, short reaction time, high efficiency, good chemoselectivity and remarkable functional group tolerance.