(3S)-3,3a,5aβ,6,6aα,8,9,10,10aα,10cβ-Decahydro-3α-hydroxy-3aβ-methyl-7H-3,10bβ-ethano-1H,4H-benzo[h]furo[4,3,2-de]-2-benzopyran-4,7-dione