InChI=1S/C17H17NO7S/c19-14-8-10-17(21,11-9-14)15(25-26(22,23)24)12-18-16(20)7-6-13-4-2-1-3-5-13/h1-11,15,21H,12H2,(H,18,20)(H,22,23,24)/b7-6+