¹H NMR (400 MHz, CDCl₃) δ 8.14 (d, J = 7.9 Hz, 2H), 7.98 (d, J = 7.9 Hz, 2H), 7.15 (dd, J = 17.1, 10.6 Hz, 1H), 6.46 (d, J = 17.1 Hz, 1H), 6.00 (d, J = 10.6 Hz, 1H), 3.96 (s, 3H). ¹³C NMR (100 MHz, CDCl₃) δ 190.6, 166.2, 140.6, 133.7, 132.2, 131.1, 129.8, 128.5, 52.4.