InChI=1S/C15H20O8S/c1-7-5-13-14(9(3)15(18)22-13)11(17)4-8(2)12(6-10(7)16)23-24(19,20)21/h5,10-14,16-17H,2-4,6H2,1H3,(H,19,20,21)/b7-5+