New procedures for the synthesis of 3 (2H)-furanones and 4-alkoxy-2 (5H)-furanones are reported. Reaction of ketones with the lithium salt of propynal diethyl acetal, followed by treatment of the resulting 4-hydroxy-2-alkynal diethyl acetals with sulfuric acid–methanol, gave 2, 2-disubstituted 3 (2H)-furanones. The action of a polymer reagent Hg/Nafion-H upon 4–hydroxy-2-alkynones produced 2, 2, 5-trisubstituted 3 (2H)-furanones. Reaction of 1, 1, ...