(3R,3aR,5aS,5bR,10aS,10bS)-3a,5b-dimethyl-3-[(2R)-6-methylheptan-2-yl]-2,3,3a,4,5,5a,5b,6,7,10,10a,10b-dodecahydrocyclopenta[a]fluoren-8(1H)-one