1H NMR (400 MHz, CDCl3) δ 7.35 (d, J = 7.9 Hz, 2H), 7.16 (d, J = 5.6 Hz, 3H), 7.12 – 7.04 (m, 3H), 6.92 (d, J = 7.9 Hz, 2H), 6.78 (d, J = 8.0 Hz, 1H), 3.84 (s, 6H), 2.33 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 196.31, 160.89, 160.40, 155.56, 137.13, 137.01, 133.31, 130.64, 130.18, 129.74, 128.85, 128.38, 125.24, 122.07, 116.08, 114.13, 110.38, 55.80, 55.30, 21.35.