InChI=1S/C15H20N2O7/c1-6(16)9(17)7-4-2-3-5-8(7)23-15-12(20)10(18)11(19)13(24-15)14(21)22/h2-5,10-13,15,18-20H,16-17H2,1H3,(H,21,22)/b9-6-