1H NMR (400 MHz, CDCl3) δ 7.23 (d, J = 7.9 Hz, 2H), 7.11 (d, J = 7.9 Hz, 2H), 6.38 (d, J = 15.8 Hz, 1H), 6.26-6.12 (m, 1H), 2.33 (s, 3H), 1.88 (d, J = 6.6 Hz, 3H); 13C{H} NMR (101 MHz, CDCl3) δ136.4, 135.2, 130.8, 129.1, 125.7, 124.6, 21.1, 18.4。