Showing structure for [4R-[4alpha(E),5aalpha,6alpha,9abeta,9balpha]]-2,4,5,5a,6,7,8,9,9a,9b-Decahydro-6-hydroxy-3-(hydroxymethyl)-5a-methyl-9-methylene-2-oxonaphtho[1,2-b]furan-4-yl ester 2-methyl-2-butenoic acid