Showing structure for (1's,2r,3's,4'as,6's,6'ar,10'ar,10'bs)-1'-(acetyloxy)-6'a-[(acetyloxy)methyl]-4'a,10'b-dimethyl-5''-oxo-octahydrodispiro[oxirane-2,7'-naphtho[2,1-b]pyran-3',3''-oxolan]-6'-yl (2e)-2-methylbut-2-enoate