Showing structure for 3,7,7,13-tetramethyl-17-oxaspiro[hexacyclo[11.7.1.0²,¹¹.0³,⁸.0¹¹,¹⁹.0¹⁵,¹⁹]henicosane-20,2'-oxirane]-4,14-diene-6,16,21-trione