[(3aR,4R,6E,9R,10Z,11aR)-9-acetyloxy-6-(hydroxymethyl)-10-methyl-3-methylidene-2-oxo-3a,4,5,8,9,11a-hexahydrocyclodeca[b]furan-4-yl] (E)-4-hydroxy-2-methylbut-2-enoate