Epimeric mono- and bis-sulfoxides synthesized by oxidation of 8-methyl-5-(methylsulfanylmethyl)-3-thiabicyclo[3.3.1]non-7-en-6-one were separated by silica gel column chromatography. Their threo and erythro isomers were distinguished by signals of diastereotopic protons of the exocyclic methylene group.