1H NMR (400 MHz, CDCl3) δ 7.51 (s, 1H), 7.41 (d, J = 4.4 Hz, 4H), 7.35-7.31 (m, 1H), 2.45 (s, 3H), 2.05 (s, 3H); 13C{H} NMR (101 MHz, CDCl3) δ 200.2, 139.5, 137.7, 135.8, 129.6, 128.5, 128.4, 25.7, 12.8。