6,6-difluoronorethisterone 6,6-difluoronorethisterone 6,6-difluoronorethisterone, also known as 6,6-difluoro-17α-ethynyl-19-nortestosterone or as 6,6-difluoro-17α-ethynylestr-4-en-17β-ol-3-one, is a steroidal progestin of the 19-nortestosterone group that was described in 1971 but was never marketed. it is a fluorinated derivative of norethisterone. the c17β acetate ester, 6,6-difluoronorethisterone acetate, has also been synthesized and described. 6,6-difluoronorethisteroneclinical dataother names6,6-difluoro-17α-ethynyl-19-nortestosterone; 6,6-difluoro-17α-ethynylestr-4-en-17β-ol-3-oneidentifiers iupac name (1s,2r,10r,11s,14s,15s)-14-ethynyl-8,8-difluoro-14-hydroxy-15-methyltetracycloheptadec-6-en-5-one cas number25450-33-3chemical and physical dataformulac20h24f2o2molar mass334.407 g·mol−13d model (jsmol)interactive image smiles c12cc3(cc(f)(f)c4=cc(=o)cc34)1cc2(o)c#c inchi inchi=1s/c20h24f2o2/c1-3-19(24)9-7-16-15-11-20(21,22)17-10-12(23)4-5-14(17)13(15)6-8-18(16,19)2/h1,10,13-16,24h,4-9,11h2,2h3/t13-,14-,15-,16+,18?,19-/m1/s1key:zntyqlfnptxsps-zbwojippsa-n