The Acid-catalyzed Reaction of the 2-Oxabicyclo[4.1.0]hept-3-en-5-one System: Isomerization from Homo-4-pyrones into 2-Furylacetone Derivatives

The monocyclopropanation of 4-pyrones with dimethyloxosulfonium methylide, using a dimethyl sulfoxide hexamethylphosphoric triamide medium in place of neat dimethyl sulfoxide, gave homo-4-pyrone derivatives, which were then rearranged into the 2-furylacetone derivatives, along with hydra ted triketones or the dehydrated naphtho[2,1-b]furan derivative, by means of strong acid catalysis at room temperature.