Oxidation of Chiral 2(5H)-Furanone Bis-Thioethers to Disulfoxides

Novel disulfinyl derivatives based on 3,4-dichloro-2(5H)-furanone, aliphatic dithiols, and monoterpene alcohols were synthesized. Chiral bis-thioethers in the molecules of which the dithiol fragment links two five-membered cycles at C4 atoms were obtained in the reactions of 5(S)-(l-menthyloxy)- and 5(S)-(l-bornyloxy)-2(5H)-furanones with ethane-1,2-dithiol and propane-1,3-dithiol in acetone in basic medium. The action of an excess of m-chloroperoxybenzoic acid (2.0–3.2 equiv.) on bis-thioethers led to the formation of the corresponding mono- and disulfoxides bearing l-menthol or l-borneol fragments at the 5th position of the lactone ring. The methods of column chromatography and fractional recrystallization were used for the isolation of individual products. The structure of the synthesized heterocycles was proved by IR and NMR spectroscopy, and their composition was confirmed by high-resolution mass spectrometry. The molecular structure of the three disulfoxides was characterized by X-ray diffraction analysis.