1H NMR (400 MHz, CDCl3) δ 7.25 (t, 2H), 7.10 (d, J = 7.8 Hz, 2H), 6.35 (d, J = 15.8 Hz, 1H), 6.26-6.16 (m, 1H), 2.32 (s, 3H), 2.27-2.17 (m, 2H), 1.09 (t, J = 7.5 Hz, 3H); 13C{H} NMR (101 MHz, CDCl3) δ 136.4, 135.2, 131.6, 129.1, 128.6, 125.8, 26.0, 21.1, 13.7。