InChI=1S/C21H20O13/c22-8-4-12(26)15(13(27)5-8)9(23)2-1-7-3-11(25)14(6-10(7)24)33-21-18(30)16(28)17(29)19(34-21)20(31)32/h1-6,16-19,21-22,24-30H,(H,31,32)/b2-1+