Showing structure for (12r,15s,16r,17r)-11,11,15-trimethyl-16-(3-methylbut-2-enoyl)-6,10,19-trioxapentacyclo[13.3.1.0²,⁷.0⁹,¹⁸.0¹²,¹⁷]nonadeca-1,3,7,9(18)-tetraen-5-one