Email-запись: Diethyl 7,8,18,19-tetra­methyl-2,13-dioxo­hexa­cyclo­[10.10.2.0(3,24).0(5,10).0(14,23).0(16,21)]tetra­cosa-5,7,9,16,18,20-hexa­ene-23,24-dicarboxyl­ate