1H NMR (400 MHz, CDCl3) δ 7.41 (d, J = 8.5 Hz, 2H), 7.19 (d, J = 8.5 Hz, 2H), 6.34 (d, J = 17.4 Hz, 1H), 6.28-6.16 (m, 1H), 1.88 (d, J = 6.4 Hz, 3H); 13C{H} NMR (101 MHz, CDCl3) δ 140.1, 129.9, 129.7, 129.6, 128.7, 127.4, 124.5, 122.7, 18.4。