Stereochemistry of hydroxylation of some chiral spiro-[2,5]octan-4-ones

Stereoselective oxidative alpha hydroxylation of (1R,5R,8R,3R)-1-aryl-5-isopropyl-8-methyl-3-spiro-[2,5]octan-4-ones has been found as a secondary process in the cyclopropanation of 2-arylidene isomenthanones with trimethylsulfoxonium iodide in DMSO/NaOH or DMF/NaOH system. Three stereoisomeric hydroxy ketones have been isolated from a reaction mixture of cyclopropanation reaction, but the reaction of oxidation carried out with isolated spiro-[2,5]octan-4-ones was stereoselective. The advantages of this method of stereoselective hydroxylation are room temperature of reaction and absence of expensive catalysts. The reduction of obtained hydroxy ketones was also stereoselective and gave the only trans-(4R,5S)-dioles. The structures have been confirmed with 1D and 2D 1H and 13C NMR, MS spectra and for stereoisomeric hydroxy ketones with X-ray analysis also.