Rare 1,6-C H insertion of naphthol- and anthrol-derived alkylidenecarbenes
has been observed in modest yield. Reaction in deuterated solvent did not p
rovide any evidence in support of a reaction mechanism that requires exchan
ge of the migrating proton with solvent. The pyran-annelated aromatic produ
cts are formed only when opportunities for the more common 1,5-C-H insertio
n process are blocked. (C) 2001 Published by Elsevier Science Ltd.