Showing structure for (4s,4as,5r,6s,8ar,9ar)-6,9a-bis(acetyloxy)-3,4a,5-trimethyl-2-oxo-4h,5h,6h,7h,8h,8ah,9h-naphtho[2,3-b]furan-4-yl (2z)-2-methylbut-2-enoate