1H NMR (400 MHz, CDCl3) δ 7.29 (d, J = 8.7 Hz, 4H), 6.88 (d, J = 8.7 Hz, 4H), 5.31 (s, 2H), 3.83 (s, 6H). 13C{H}NMR (101 MHz, CDCl3) δ 159.3, 149.0, 134.3, 129.4, 113.5, 111.6, 55.3。