NMR:
1H NMR (600 MHz, DMSO-d6) δ 10.28 (br s, 1H), 7.98 (m, 1H), 7.90 (d, J = 8.4 Hz, 2H), 7.82 (d, J = 8.4 Hz, 2H), 7.71 (t, J = 7.2 Hz, 2H), 7.37 (s, 1H), 7.17 (d, J = 8.4 Hz, 1H), 7.11 (br s, 2H), 6.85 (t, J = 6.0 Hz, 1H), 6.22 (s, 1H), 2.00 (s, 3H).
13C NMR (150 MHz, DMSO-d6) δ 162.0, 155.4, 153.7, 147.0, 141.0, 138.2, 133.2, 131.3, 128.7, 128.2, 121.9, 115.4, 114.4, 103.4, 100.4, 15.7.
