1H NMR (400 MHz, CDCl3) δ 7.60 (d, J = 8.2 Hz, 4H), 7.45 (d, J = 8.0 Hz, 4H), 5.74 (s, 2H), 2.68 (s, 6H). 13C{H} NMR (101 MHz, CDCl3) δ 149.8, 138.8, 137.2, 128.8, 128.1, 112.8, 21.0。