1H NMR (400 MHz, CDCl3) δ 7.42 (d, J = 7.1 Hz, 2H), 7.35 (t, J = 7.1 Hz, 2H), 7.30 (s, 1H), 7.26 (d, J = 3.5 Hz, 1H), 7.08 (s, 1H), 7.01 (s, 1H), 6.18 (s, 1H), 4.97 (d, J = 9.2 Hz, 1H), 4.54 (s, 2H), 2.83 (dd, J = 21.5, 12.8 Hz, 2H). 13C NMR(100 MHz, CDCl3) δ 145.3, 140.0, 133.9, 128.5, 127.5, 126.6, 124.9, 124.9, 124.1, 122.2, 71.8, 66.6, 34.7.