Stereoisomerism in the representative tetracyclic dispiro ozonide derived from (methylene)dicyclohexanone with the 1,5-diketo arrangement

The conditions and reasons for the stereoselective transformation of the rac form of 2,2′-(methylene)-dicyclohexanone into the meso- or rac-diastereomer of tetracyclic dispiro ozonide (1,2,4-trioxolane) in the reaction with 30% aqueous H₂O₂ in the presence of acid have been determined. A mechanism for the stereoisomerization of ozonides was proposed, and the stereochemistry of diastereomeric ozonides was established by NMR data.