InChI=1S/C18H20O6S/c1-3-17(13-4-8-15(20)9-5-13)18(12(2)19)14-6-10-16(11-7-14)24-25(21,22)23/h4-12,19-20H,3H2,1-2H3,(H,21,22,23)/b18-17-