InChI=1S/C21H20O7/c1-21(2)18(24)8-14-17(28-21)9-16-13(19(14)26-3)7-12(20(25)27-16)11-5-4-10(22)6-15(11)23/h4-7,9,18,22-24H,8H2,1-3H3