(6aR,6bS,7S,8aS,8bS,12aS,12bS)-7,11a-dihydroxy-6a,8a-dimethyl-6b,7,8,8a,8b,10,11a,12,12a,12b-decahydro-1H-naphtho[2′,1′:4,5]indeno[2,1-b]furan-4,9(2H,6aH)-dione