1H NMR (400 MHz, CDCl3) δ 8.27 (d, J = 7.6 Hz, 2H), 8.20 (d, J = 8.5 Hz, 1H), 7.91 (d, J = 8.5 Hz, 1H), 7.67 (d, J = 8.1 Hz, 1H), 7.60-7.51 (m, 3H), 7.49 – 7.40 (m, 2H), 2.92 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 155.6, 147.0, 139.7, 137.6, 137.2, 129.9, 129.3, 128.8, 127.6, 127.1, 126.1, 125.4, 118.3, 17.9.