1H NMR (400 MHz, CDCl3) δ 8.58 (s, 1H), 7.32 (d, J = 8.7 Hz, 2H), 6.97 (d, J = 8.7 Hz, 2H), 3.85 (s, 3H); 13C NMR (101 MHz, CDCl3) δ 160.5 (s), 159.5 (s), 130.2 (s), 116.6 (s), 116.4 (s), 114.4 (s), 55.3 (s). HRMS (EI): calculated for C10H8N2O4: 220.0484; found: 220.0487.