Acetolysis of the adduct of diethoxyoxophosphoranesulphenyl chloride (I) and cyclohexene- 4-carboxylic acid chloride (IV), yields, via an intramolecular reaction, nearly equal amounts of 4-acetylthio-6-oxabicyclo [3.2. 1] octan-7-one (XIV) and 4-acetoxy-6-thiabicyclo [3.2. 1] octan-7-one (XVIII) and accounts for about 90% of the products. The 4-acetylthio group in XIV and the 4-acetoxy group in XVIII occupy axial positions. The results testify to the high ...