3H-9,6-(Epoxymethano)-7,9b-methanoazuleno- [1,8-cd]pyran-12-one,3a,4,5,5a,6,7,8,9- octahydro-3-hydroxy-6-methyl-,(3R,3aR,- 5aR,6R,7S,9S,9bS)-