InChI=1S/C19H20O6S/c20-17(12-11-16-6-2-4-8-19(16)21)7-3-1-5-15-9-13-18(14-10-15)25-26(22,23)24/h2-4,6-10,13-14,21H,1,5,11-12H2,(H,22,23,24)/b7-3+