InChI=1S/C20H20N2O4/c1-25-17-7-3-15(4-8-17)11-19(21-13-23)20(22-14-24)12-16-5-9-18(26-2)10-6-16/h3-14H,1-2H3,(H,21,23)(H,22,24)/b19-11-,20-12-