1H NMR (400 MHz, CDCl3) δ 9.95 (s, 1H), 7.22 (d, J = 7.5 Hz, 4H), 7.14 (d, J = 7.5 Hz, 4H), 4.85 (s, 1H), 2.38 (s, 6H). 13C NMR (101 MHz, CDCl3) δ 198.77, 137.24, 133.43, 129.63, 128.96, 63.39, 21.03. GC-MS (m/z): 224。