Showing structure for (1r,18r,21s)-9,12,13,14-tetramethoxy-21-methyl-5,7,20-trioxapentacyclo[16.2.1.0²,¹⁰.0⁴,⁸.0¹¹,¹⁶]henicosa-2(10),3,8,11(16),12,14-hexaene