Structures of the sulphones formed in the oxidation of the products of thiol addition to chloronorbornadienes and related compounds

The sulphides formed by the respective additions of ethanethiol and benzenethiol to some chloronobornadienes are converted into the corresponding sulphones without change in stereochemistry. The only exceptions are the oxidation, with hydrogen peroxide in acetic acid, of 1,4,5,6,7,7-hexachloronorborn-5-en-2-endo-yl phenyl sulphide to afford the 2-exo phenyl sulphone, and of 1,2,3,5-endo,6,6-hexachloronoborn-2-en-7-syn-yl phenyl sulphide to give an epimeric mixture of the corresponding 7-syn and 7-anti phenyl sulphones. Product sulphones have been treated with potassium t-butoxide in t-butyl alcohol in an effort to effect epimerisation, and to provide evidence about the thermodynamic stability of individual sulphones. It is probable that in the presence of potassium t-butoxide in t-butyl alcohol, many of the derived carbanions have complete configurational stability, and hence the sulphones are not epimerised.