InChI=1S/C19H18O7S/c1-13(12-20)2-6-16-8-14(5-7-19(16)26-27(23,24)25)3-4-15-9-17(21)11-18(22)10-15/h2-11,20-22H,1,12H2,(H,23,24,25)/b4-3+,6-2+