InChI=1S/C20H20O6/c1-2-3-4-5-13(22)18-14(23)8-11-6-10-7-12(21)9-15(24)16(10)19(25)17(11)20(18)26/h7-9,21,23-24,26H,2-6H2,1H3/p-1