1H NMR (400 MHz, CDCl3) δ 7.42 (s, 5H), 7.27 (s, 5H), 7.22 (s, 1H), 7.07 (d, J = 7.8 Hz, 1H), 6.82 (d, J = 7.9 Hz, 1H), 3.88 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 196.17, 161.07, 156.36, 136.96, 132.97, 131.40, 130.99, 129.84, 129.31, 128.74, 128.46, 128.04, 127.92, 127.48, 122.25, 116.34, 110.61, 55.84.