InChI=1S/C18H18N2O4/c1-9-12(4-6-17(22)23)10(2)19-16(9)8-14-13-7-11(21)3-5-15(13)20-18(14)24/h3,5,7-8,19,21H,4,6H2,1-2H3,(H,20,24)(H,22,23)/b14-8-