InChI=1S/C18H20N2O4/c19-13(18(23)24)6-11-7-15(17(22)9-16(11)21)20-14-8-12(14)10-4-2-1-3-5-10/h1-5,9,11-14,22H,6-8,19H2,(H,23,24)/b20-15+