17-trifluorovinyl-3-methyl ether of 17-.beta.-estradiol 19-Nor-17.alpha.-pregna-1,3,5(10),20-tetraen-17-ol, 20,21,21-trifluoro-3-methoxy- 19-Norpregna-1,3,5(10),20-tetraen-17-ol, 20,21,21-trifluoro-3-methoxy-, (17.alpha.)- 20,21,21-trifluoro-3-methoxy-19-nor-17.alpha.pregna-1,3,5(10),20-tetraen-17-ol 5210-10-6 NSC73865