Showing structure for (3as,4s,5r,5as,6r,9as,9bs)-5-hydroxy-5a,9-dimethyl-6-{[(2z)-2-methylbut-2-enoyl]oxy}-3-methylidene-2-oxo-3ah,4h,5h,6h,7h,9ah,9bh-naphtho[1,2-b]furan-4-yl (2s,3r)-2,3-dimethyloxirane-2-carboxylate