Lead tetraacetate–iodine oxidation of 23-spirostanols

Reactions of 23R- and 23S-23-spirostanols in the 25R and 25S series with lead tetraacetate–iodine were studied. The reactions carried out at low temperature afforded d-seco-iododialdehydes and C22 lactones, while similar reactions performed in refluxing tetrachloromethane yielded 20-chlorolactones and their 21-acetoxy derivatives irrespective of the hydroxyl group configuration at C-23. The reaction mechanisms are discussed.