InChI=1S/C18H18Br2N2O3/c1-18(2,3)12-6-4-10(5-7-12)17(25)22-21-9-11-8-13(19)16(24)14(20)15(11)23/h4-9,23-24H,1-3H3,(H,22,25)/b21-9+