InChI=1S/C21H20O13/c22-8-3-7(4-9(23)5-8)1-2-10(24)13-11(25)6-12(14(26)15(13)27)33-21-18(30)16(28)17(29)19(34-21)20(31)32/h1-6,16-19,21-23,25-30H,(H,31,32)/b2-1+