1H NMR (400 MHz, CDCl3): δ 7.87 (d, J = 7.9 Hz, 2H), 7.28 (d, J = 7.8 Hz, 2H), 7.16 (dd, J = 17.1, 10.5 Hz, 1H), 6.43 (d, J = 17.1 Hz, 1H), 5.90 (d, J = 10.5 Hz, 1H), 2.42 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 190.5, 143.8, 134.7, 132.3, 129.7, 129.3, 128.8, 21.7.