InChI=1S/C18H20O6S/c1-3-15(12-5-8-14(19)9-6-12)16(4-2)13-7-10-17(20)18(11-13)24-25(21,22)23/h5-11,19-20H,3-4H2,1-2H3,(H,21,22,23)/b16-15-