1H,7H-Naphtho[1,8-bc:4,4a-c']difuran-5,10a(8H)-dicarboxylicacid, 10-(acetyloxy)-4-[(1aR,2S,3aS,6aS,7S,7aS)-hexahydro-6a-hydroxy-7-methyl-2,7-methanofuro[2,3-b]oxireno[e]oxepin-1a(2H)-yl]octahydro-3,5-dihydroxy-4-methyl-8-(2-methyl-1-oxobutoxy)-,dimethyl e