pregnane pregnane pregnane, also known as 17β-ethylandrostane or as 10β,13β-dimethyl-17β-ethylgonane, is a c21 steroid and, indirectly, a parent of progesterone. it is a parent hydrocarbon for two series of steroids stemming from 5α-pregnane (originally allopregnane) and 5β-pregnane (17β-ethyletiocholane). it has a gonane core. pregnane names iupac name 5ξ-pregnane systematic iupac name (1s,3as,3bs,5aξ,9as,9bs,11ar)-1-ethyl-9a,11a-dimethylhexadecahydro-1h-cyclopentaphenanthrene identifiers cas number 481-26-5 y 3d model (jsmol) interactive image chebi chebi:8386 y chemspider 5256760 y pubchem cid 6857422 unii 10z78hhv4c y comptox dashboard (epa) dtxsid10425881 inchi inchi=1s/c21h36/c1-4-15-9-11-18-17-10-8-16-7-5-6-13-20(16,2)19(17)12-14-21(15,18)3/h15-19h,4-14h2,1-3h3/t15-,16?,17-,18-,19-,20-,21+/m0/s1 ykey: jwmfygxqpxqeem-wzbaxqlosa-n yinchi=1/c21h36/c1-4-15-9-11-18-17-10-8-16-7-5-6-13-20(16,2)19(17)12-14-21(15,18)3/h15-19h,4-14h2,1-3h3/t15-,16?,17-,18-,19-,20-,21+/m0/s1key: jwmfygxqpxqeem-wzbaxqlobz smiles c41cccc1(3(2cc(2(c)cc3)cc)cc4)c properties chemical formula c21h36 molar mass 288.511 g/mol density 0.926 g/ml except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references 5β-pregnane is the parent of pregnanediones, pregnanolones, and pregnanediols, and is found largely in urine as a metabolic product of 5β-pregnane compounds. pregnanes steroid nomenclature: pregnanes have carbons 1 through 21. pregnanes are steroid derivatives with carbons present at positions 1 through 21. most biologically significant pregnane derivatives fall into one of two groups: pregnenes and pregnadienes. another class is pregnatrienes. pregnenes cortisone pregnenes have a double bond. examples include: cortisone hydrocortisone progesterone pregnadienes main article: pregnadiene cyproterone acetate pregnadienes have two double bonds. examples include: cyproterone acetate danazol fluocinonide