1,6-CH insertion of alkylidenecarbenes in 1-naphthol and 1-anthrol derivatives

Rare 1,6-CH insertion of naphthol- and anthrol-derived alkylidenecarbenes has been observed in modest yield. Reaction in deuterated solvent did not provide any evidence in support of a reaction mechanism that requires exchange of the migrating proton with solvent. The pyran-annelated aromatic products are formed only when opportunities for the more common 1,5-CH insertion process are blocked.