Synthesis of Propargyl (±)-(5-Methylidene-4-oxopent-2-en-1-yl)Acetate

The synthesis of propargyl (±)-(5-methylidene-4-oxocyclopent-2-en-1-yl)acetate from a methoxycarbonyl precursor is described. The synthesis includes the stages of formation of a Michael adduct with thiophenol at the terminal double bond, Luche reduction of the keto group, alkaline hydrolysis of the ester function, and alkylation of the acid with propargyl bromide to obtain carboxy-protected cyclopentenol. The latter is converted into ketosulfone by oxidation with the Dess–Martin reagent and then by treatment with 30% hydrogen peroxide. The elimination of PhSO 2 H from ketosulfone leads to the target molecule.