(3aR,3bS,5aS,6S,8aS,8bS)-6-[(1R)-1-hydroxyethyl]-3a,5a-dimethyl-3a,3b,4,5,5a,6,7,8,8a,8b,9,10-dodecahydrodicyclopenta[a,f]naphthalen-2(3H)-one