1H NMR (400 MHz, CDCl3) δ 10.36 (s, 1H), 9.10 (d, J = 9.1 Hz, 1H), 8.24 (s, 1H), 8.02 (d, J = 7.3 Hz, 1H), 7.93 (d, J = 9.0 Hz, 1H), 7.88 (d, J = 8.1 Hz, 2H), 7.54 (d, J = 7.3 Hz, 1H), 7.20 (d, J = 8.1 Hz, 2H). 13C NMR (101 MHz, CDCl3) δ 192.89, 144.91, 138.49, 137.84, 137.54, 136.42, 135.03, 133.33, 131.43, 130.87, 129.73, 126.88, 126.83, 94.51, 93.99.