1H NMR (400 MHz, CDCl3) δ 6.89 (s, 2H), 6.47 (d, J = 13.2 Hz, 1H), 5.64 (d, J = 13.2 Hz, 1H), 3.72 (s, 3H), 2.30 (s, 6H), 2.28 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 150.55, 136.49, 135.39, 131.32, 128.42, 101.23, 56.11, 21.14, 20.84. GC-MS (m/z): 176。