¹H NMR (400 MHz, DMSO-d₆) δ 12.05 (s, 1H), 7.09 (d, J = 8.1 Hz, 2H), 6.77 (d, J = 8.1 Hz, 2H), 5.99 (dd, J = 17.6, 10.9 Hz, 1H), 5.15 (d, J = 17.6 Hz, 1H), 4.59 (d, J = 10.9 Hz, 1H). ¹³C{H} NMR (101 MHz, DMSO-d₆) δ 167.0, 141.2, 135.8, 129.9, 129.6, 126.2, 116.9。