Preparation of gamma-pyrones from 3-substituted furans

Abstract From the Canadian patent

Gamma-pyrones are prepared by contacting a 3-halo-furfuryl alcohol or a 3-alkoxy-furfuryl alcohol with one equivalent of a halogen, peracid or peroxide oxidant and then heating until hydrolysis of the formed 4-substituted-dihydropyran intermediate is substantially complete. Maltol (2-methyl-3-hydroxy-4H-pyran- 4-one) is prepared by this process from 2-(1-hydroxyethyl)-3alkoxy furans or 2-(1-hydroxyethyl)-3-halo-furans. Gamma-pyrones are also prepared by contacting the corresponding 3-substituted- 2,5-dialkoxy-furfuryl alcohols with acid until conversion to the gamma-pyrones is substantially complete.