InChI=1S/C21H29NO7S/c23-21(22-12-6-7-13-22)15-18(29-30(24,25)26)9-5-3-1-2-4-8-17-10-11-19-20(14-17)28-16-27-19/h4,8,10-11,14,18H,1-3,5-7,9,12-13,15-16H2,(H,24,25,26)/b8-4+