pentarane a pentarane a pentarane a, also known as d'6-pentarane or pregna-d'6-pentarane, as well as 16α,17α-cyclohexanoprogesterone, 16α,17α-tetramethylenepregn-4-ene-3,20-dione, or 17α-acetyl-16β,24-cyclo-21-norchol-4-en-3-one, is a steroidal progestin that was developed by the zelinskii institute of organic chemistry of the russian academy of sciences and was never marketed. the 6α-methylated analogue of pentarane a is known as mecigestone or as pentarane b. pentarane aclinical dataother namesd'6-pentarane; pregna-d'6-pentarane; 16α,17α-cyclohexanoprogesterone; 16α,17α-tetramethylenepregn-4-ene-3,20-dione; 17α-acetyl-16β,24-cyclo-21-norchol-4-en-3-oneidentifiers iupac name (4ar,4bs,6as,6bs,10ar,11as,11br)-6b-acetyl-4a,6a-dimethyl-4,4b,5,6,7,8,9,10,10a,11,11a,11b,12,13-tetradecahydro-3h-indenophenanthren-2-one cas number38522-51-9pubchem cid189105chemspider164309comptox dashboard (epa)dtxsid20959389 chemical and physical dataformulac25h36o2molar mass368.561 g·mol−13d model (jsmol)interactive image smiles cc(=o)12cccc1c32(cc43ccc5=cc(=o)cc45c)c inchi inchi=1s/c25h36o2/c1-16(26)25-11-5-4-6-18(25)15-22-20-8-7-17-14-19(27)9-12-23(17,2)21(20)10-13-24(22,25)3/h14,18,20-22h,4-13,15h2,1-3h3/t18-,20-,21+,22+,23+,24+,25+/m1/s1key:qrvbgqltpqqfjy-iehcjhdvsa-n