InChI=1S/C21H25NO8S/c1-27-15-10-19(29-3)16(20(11-15)30-4)7-8-31(25,26)13-14-5-6-18(28-2)17(9-14)22-12-21(23)24/h5-11,22H,12-13H2,1-4H3,(H,23,24)/b8-7+