2-Butenoic acid, 2-methyl-, 6-(acetyloxy)-2,3,3a,4,5,6,6a,7,8,9b-decahydro-3,3a-dihydroxy-3,6,9-trimethyl-2-oxo-4-(1-oxobutoxy)azuleno(4,5-b)furan-8-yl ester, (3S-(3alpha,3abeta,4alpha,6beta,6abeta,8alpha(Z),9balpha))-