InChI=1S/C21H21BrN4O4/c1-28-17-11-14(12-18(29-2)19(17)22)13-23-25-21(27)20(30-3)15-5-7-16(8-6-15)26-10-4-9-24-26/h4-13,20H,1-3H3,(H,25,27)/b23-13+