An unusual epimerization of a thioether

Reaction of 6-exo-methylthio-2-exo-phenylbicyclo[2.2.1]heptan-2-endo-ol with sodium azide and acid afforded the corresponding 2-exo-azide. This azide was reduced and acetylated to give a crystalline derivative whose structure was unequivocally established by X-ray crystallographic analysis. Surprisingly, the isomeric 6-endo-methylthio-2-exo-phenylbicyclo[2.2.1]heptan-2-endo-ol on reaction with sodium azide and acid yielded the same azide as the 6-exo-methylthio analogue. Evidence for the mechanism of thioisomerization is presented. [GRAPHICS] .