Reacting Cyclopropenones with Arynes: Access to Spirocyclic Xanthene–Cyclopropene Motifs

A formal insertion of two aryne moieties into the carbon–oxygen double bond of cyclopropenone has been realized. Spirocyclic xanthene–cyclopropene scaffolds were obtained. Mechanistically, a sequence of a formal [2 + 2]-cycloaddition followed by electrocyclic ring opening and a terminating [4 + 2]-type cycloaddition is postulated. The use of an electron-rich aryne precursor led to ring cleavage of the cyclopropene to afford an unprecedented xanthylium salt.