The addition of ethanethiol and methanethiol to hexachloronorbornadiene

The free-radical addition of ethanethiol and methanethiol to hexachloronorbornadiene is shown to give as main products, 1,4,5,6,7,7-hexachloronorborn-5-en-2-endo-yl alkyl sulphides and 1,2,3,5-endo,6,6-hexachloro-norborn-2-en-7-syn-yl alkyl sulphides. On oxidation of these sulphides to sulphones epimerisation occurs at C-2 and C-7, respectively. The structure of the Diels–Alder adduct of ethyl vinyl sulphone and hexachlorocyclopentadiene is established as 1,4,5,6,7,7-hexachloronorborn-5-en-2-exo-yl ethyl sulphone. Treatment of 1,2,3,5-endo,6,6-hexachloronorborn-2-en-7-syn-yl alkyl sulphides and the corresponding 7-anti-sulphones with an equimolar quantity of potassium t-butoxide results in the elimination of hydrogen chloride to give 1,2,3,5,6-pentachloronorborna-2,5-dien-7-yl alkyl sulphides and sulphones, respectively.