NMR (400 MHz, CDCl3) δ 10.37 (s, 1H), 9.35 (d, J = 9.2 Hz, 1H), 8.01 (d, J = 7.3 Hz, 1H), 7.85 (d, J = 2.1 Hz, 1H), 7.65 (dd, J = 9.2, 2.2 Hz, 1H), 7.59 (d, J = 7.3 Hz, 1H), 7.55 – 7.51 (m, 2H), 7.42 – 7.39 (m, 2H). 13C NMR (101 MHz, CDCl3) δ 192.98, 145.14, 137.49, 136.23, 134.67, 133.59, 132.92, 130.96, 130.85, 129.73, 129.19, 128.96, 127.11, 125.23.