In 20 ml of acetone is dissolved 0.61 g of pivalic acid, and 3.0 ml of 2N-NaOH and 10 ml of water are added. And then, 1.2 g of 16β-ethyl-17β-bromoacetoxy-4-estren-3-one and 30 ml of DMF are added and the mixture is refluxed for 6 hours. After cooling, 150 ml of ethyl acetate is added and the organic layer is separated. The aqueous layer is is further extracted with 50 ml of ethyl acetate. The organic layers are combined, washed with water and saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent is then distilled off under reduced pressure and the residue is subjected to column chromatography, elution being carried out with 400 ml of diisopropyl ether. The eluate is evaporated under reduced pressure to remove the solvent, giving 1.1 g of the above-identified compound as a colorless viscous oil.
