clostebol propionate clostebol propionate clostebol propionate (brand name yonchlon), also known as 4-chlorotestosterone 17β-propionate or as 4-chloroandrost-4-en-17β-ol-3-one 17β-propionate, is a synthetic, injected anabolic-androgenic steroid (aas) and a derivative of testosterone. it is an androgen ester – specifically, the c17β propionate ester of clostebol (4-chlorotestosterone) – and acts as a prodrug of clostebol in the body. clostebol acetate is administered via intramuscular injection. not to be confused with clobetasol propionate. clostebol propionateclinical datatrade namesyonchlonroutes ofadministrationintramuscular injectionidentifiers iupac name phenanthren-17-yl] propanoate cas number2162-44-9pubchem cid71586790chemspider32698327unii7jj3052noucomptox dashboard (epa)dtxsid70176009 chemical and physical dataformulac22h31clo3molar mass378.94 g·mol−13d model (jsmol)interactive image smiles ccc(=o)o1cc21(cc32ccc4=c(c(=o)cc34c)cl)c inchi inchi=1s/c22h31clo3/c1-4-19(25)26-18-8-7-14-13-5-6-16-20(23)17(24)10-12-21(16,2)15(13)9-11-22(14,18)3/h13-15,18h,4-12h2,1-3h3/t13-,14-,15-,18-,21+,22-/m0/s1key:wnubdfjmqbmnqb-dxodlalxsa-n