1H NMR (400 MHz, CDCl3) δ 8.19-8.04 (m, 4H), 7.81 (d, J = 8.6 Hz, 1H), 7.56-7.49 (m, 4H), 7.44 (t, J = 7.2 Hz, 1H), 2.53 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 156.5, 146.8, 139.8, 136.2, 136.2, 132.0, 129.4, 129.2, 128.8, 127.5, 127.2, 126.4, 119.0, 21.6.