InChI=1S/C21H22O11S/c1-5-11(2)20(24)31-18-16-14(8-6-13-7-9-15(23)30-17(13)16)29-19(18)21(4,32-12(3)22)10-28-33(25,26)27/h5-9,18-19H,10H2,1-4H3,(H,25,26,27)/b11-5+