InChI=1S/C20H16O7S/c1-26-20-18(21)15-4-2-3-12-7-10-14(17(16(12)15)19(20)22)11-5-8-13(9-6-11)27-28(23,24)25/h2-10,18,20-21H,1H3,(H,23,24,25)