¹H NMR (400 MHz, CDCl₃) δ 7.42 (s, 4H), 6.77 (dd, J = 17.6, 10.9 Hz, 1H), 5.77 (dd, J = 17.6, 1.0 Hz, 1H), 5.26 (dd, J= 10.9, 1.0 Hz, 1H), 1.39 (s, 9H). ¹³C{H} NMR (101 MHz, CDCl₃) δ 150.8, 136.6, 134.8, 125.9, 125.4, 113.0, 34.6, 31.3。