Palladium-Catalyzed Intramolecular ipso-Friedel-Crafts Allylic Alkylation of Phenols via Arylative Activation of Allenes

A novel and efficient synthetic method for functionalized spiro[4.5]cyclohexadienones was developed based on the palladium-catalyzed sequential process: Heck insertion to an allene-intramolecular ipso-Friedel-Crafts allylic alkylation cascade. Using 5mol% of palladium catalyst, a wide variety of spirocycles was obtained in good to excellent yields. The developed cascade process was also applicable to the synthesis of tetrahydronaphthalene derivatives.