InChI=1S/C19H20O6S/c20-17(9-6-15-4-2-1-3-5-15)10-11-18(21)14-16-7-12-19(13-8-16)25-26(22,23)24/h1-5,7-8,10-13,18,21H,6,9,14H2,(H,22,23,24)/b11-10+