osaterone osaterone osaterone (developmental code name tzp-5258), also known as 17α-hydroxy-6-chloro-2-oxa-6-dehydroprogesterone, as well as 2-oxachloromadinone, is a steroidal antiandrogen and progestin that was never marketed. the c17α acetate ester of osaterone, osaterone acetate, in contrast, has been marketed. this article is about a non-clinically used antiandrogen compound. for the pharmaceutical drug, see osaterone acetate. osateroneclinical dataother namestzp-5258; gestoxarone; 2-oxachloromadinone; 17α-hydroxy-6-chloro-2-oxa-6-dehydroprogesterone; 17α-hydroxy-6-chloro-2-oxapregna-4,6-diene-3,20-dioneidentifiers iupac name (1r,3as,3br,9ar,9bs,11as)-1-acetyl-5-chloro-1-hydroxy-9a,11a-dimethyl-2,3,3a,3b,9,9b,10,11-octahydroindenoisochromen-7-one cas number105149-04-0pubchem cid3047806chemspider2310122uniixpi95tlo4ocomptox dashboard (epa)dtxsid40883157 chemical and physical dataformulac20h25clo4molar mass364.87 g·mol−13d model (jsmol)interactive image smiles cc(=o)1(cc21(cc32c=c(c4=cc(=o)oc34c)cl)c)o inchi inchi=1s/c20h25clo4/c1-11(22)20(24)7-5-14-12-8-16(21)15-9-17(23)25-10-18(15,2)13(12)4-6-19(14,20)3/h8-9,12-14,24h,4-7,10h2,1-3h3/t12-,13+,14+,18-,19+,20+/m1/s1key:zlloifneewyatc-xmuhmhrvsa-n