InChI=1S/C16H16O6S/c1-21-16-11-14(17)9-8-13(16)6-2-4-12-5-3-7-15(10-12)22-23(18,19)20/h2-5,7-11,17H,6H2,1H3,(H,18,19,20)/b4-2+