1H NMR (400 MHz, CDCl3) δ 8.20-8.12 (m, 4H), 7.84-7.78 (m, 2H), 7.70 (t, J = 7.7 Hz, 1H), 7.49 (t, J = 7.5 Hz, 1H), 7.05 (d, J = 7.9 Hz, 2H), 3.88 (s, 3H). 13C NMR (100MHz, CDCl3) δ 160.9, 156.9, 148.2, 136.7, 132.2, 129.6, 129.5, 128.9, 127.5, 126.9, 126.0, 118.6, 114.3, 55.4.