1H NMR: d=9.16 (s, 1 H), 8.92 (s, 2 H), 7.52 (d, J=8.4 Hz, 2H), 7.04 (d, J=8.4 Hz, 2 H), 3.87 (s, 3H). 13C NMR (101 MHz, CDCl3) δ160.4, 156.7, 154.3, 133.8, 128.0, 126.4, 114.8, 55.3