In 10 ml of methylene chloride was dissolved 0.50 g of 1α,3β-dihydroxypregna-5,7-diene-20-carbaldehyde, followed by addition of 1 ml of 3,4-dihydropyran and 0.05 g of p-toluenesulfonic acid. The mixture was stirred at room temperature for 2 hours. The reaction mixture thus obtained was diluted with ether, washed successively with aqueous sodium hydrogen carbonate solution and aqueous sodium chloride solution, and dried over sodium sulfate, followed by concentration under reduced pressure. Finally the concentrate was purified by column chromatography to give 0.48 g of 1α,3β-bis(tetrahydropyran-2-yloxy)pregna-5,7-diene-20-carbaldehyde showing the following physical properties.
