6H-9,4a-(Epoxymethano)-3aH,9H-cyclopenta(c)furo(2,3-b)furo(3',2':3,4)cyclopenta(1,2-d)furan-2,6,13(1H)-trione, 11-(1,1-dimethylethyl)hexahydro-1,4b-dihydroxy-5-methyl-, (3aR,4aR,4bR,5S,7aS,8aS,9R,11S, 11aS)-