1H NMR (400 MHz, CDCl3) δ 8.20-8.11 (m, 4H), 7.85 (d, J = 8.6 Hz, 1H), 7.73 (d, J = 8.6 Hz, 1H), 7.54-7.45 (m, 4H). 13C NMR (100 MHz, CDCl3) δ 158.2, 148.6, 139.1, 136.6, 135.5, 131.0, 129.7, 128.9, 128.7, 127.6, 127.3, 125.5, 119.1.