Showing structure for [1aR-(1aalpha,3alpha,4beta,4abeta,5beta,9aS*)]- 5-(Acetyloxy)-1a,2,4,4a,5,9-hexahydro-4,4a,6-trimethyl-3H-oxireno[8,8a]naphtho[2,3-b]furan-3-yl ester 2-methyl-2-propenoic acid