To a solution of 5 mg (0.0106 mmole) of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxypregna-5,7-dien-3β-yl acetate in 2 ml of dry methanol was added 7.3 mg (0.0528 mmole) of anhydrous potassium carbonate and the mixture was stirred at room temperature for 2 hours. The reaction mixture was filtered through a glass filter with the aid of Celite and the filtrate was concentrated under reduced pressure. Finally the concentrate was purified by silica gel chromatography (eluent:ethyl acetate-hexane=1:5, v/v) to give 4 mg of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxypregna-5,7-dien-3β-ol (yield: ca. 90%).
