1H NMR (400 MHz, CDCl3) δ 9.75 (s, 1H), 7.30 (d, J = 5.1 Hz, 1H), 7.09 – 7.04 (m, 1H), 6.96 (d, J = 2.8 Hz, 1H), 3.90 (s, 2H). 13C NMR (101 MHz, CDCl3) δ 197.48, 132.72, 127.45, 127.20, 125.51, 43.95. GC-MS (m/z): 126。
