Photochemical Synthesis of Five-Membered Zirconacyclocumulene Complex and Its Reactions with Ketones

Upon UV irradiation of zirconocene acetylides, five-membered zirconacyclocumulenes are formed. Subsequent photoexcitation or thermal activation of the mixture of tert-butyl-substituted complex with ketones leads to their mono- and/or diinsertion with the formation of zirconadihydrofuran and/or nine-membered dioxazirconacyclocumulene complexes, containing the [3]cumulene group in the ring. A combination of photochemical and thermal exposure enables sequential reactions of the tert-butyl-substituted complex with two different ketones.