An Efficient Oxyfunctionalization of Quinopimaric Acid Derivatives with Ozone

An access to oxyfunctionalized quinopimaric acid derivatives is reported. The ozonolysis of methyl dihydroquinopimarate occurs through 1,2-cycloaddition of ozone to the bridging double bond followed by intermolecular rearrangements and formation of nontrivial 4β-hydroxy-4α,14α-epoxy-13(15)-ene derivative 2. The oxidation of methyl furfurilydene dihydroquinopimarate with ozone led to anhydride 5and unexpected carboxymethyl substituted cyclopentane lactone 6. The structure of compound 6was confirmed by X-Ray analysis of its methyl ester.