InChI=1S/C21H20O9S/c1-27-20-10-14(5-7-17(20)23)19-12-15(22)11-16(29-19)6-3-13-4-8-18(21(9-13)28-2)30-31(24,25)26/h3-11,19,23H,12H2,1-2H3,(H,24,25,26)/b6-3+