In 20 ml of toluene are dissolved 1.5 g of 16β-ethyl-17β-hydroxy-4,9(10)-estradien-3-one and 1.92 g of 4-dimethylaminopyridine, and 1.6 ml of n-hexanoyloxyacetyl chloride is added. The mixture is stirred at 50°-60° C. for 3 hours. After cooling to 25° C., the mixture is poured into a mixture of ethyl acetate (200 ml) and saturated aqueous sodium hydrogen carbonate (50 ml). The organic layer is separated and the aqueous layer is extracted with ethyl acetate. These 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 chromatographed on a silica gel column. Following passage of diisopropyl ether-n-hexane (1:1), elution is carried out with 1000 ml of a 3:2 mixture of the same solvents. The eluate is evaporated under reduced pressure to remove the solvent, giving 1.69 g of the above-identified compound as a light-yellow viscous oil.
