InChI=1S/C21H20O7/c1-11-20(24)17(23)9-19(27-11)28-14-6-7-15-18(8-14)26-10-16(21(15)25)12-2-4-13(22)5-3-12/h2-8,10-11,17,19-20,22-24H,9H2,1H3/t11-,17-,19-,20+/m0/s1