InChI=1S/C18H18N2O8/c1-6-10-8(4-5-19-6)7-2-3-9(21)15(11(7)20-10)27-18-14(24)12(22)13(23)16(28-18)17(25)26/h2-5,12-14,16,18,20-24H,1H3,(H,25,26)