InChI=1S/C19H18O7S/c1-11(2)18-19(25-18)16-9-12(5-6-17(16)26-27(22,23)24)3-4-13-7-14(20)10-15(21)8-13/h3-10,18-21H,1H2,2H3,(H,22,23,24)/b4-3+