InChI=1S/C15H20N2O8/c1-5(16)9(17)7-4-6(2-3-8(7)18)24-15-12(21)10(19)11(20)13(25-15)14(22)23/h2-4,10-13,15,18-21H,16-17H2,1H3,(H,22,23)/b9-5-