¹H NMR (400 MHz, CDCl3) δ 12.51 (s, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.48 (t, J = 7.7 Hz, 1H), 7.40 (d, J = 7.4 Hz, 2H), 7.33 (t, J = 7.3 Hz, 2H), 7.23 (d, J = 6.6 Hz, 1H), 7.01 (d, J = 8.4 Hz, 1H), 6.91 (t, J = 7.5 Hz, 1H), 6.17 (s, 1H), 3.69 – 3.55 (m, 1H), 2.61 (s, 2H), 2.58 – 2.40 (m, 2H), 2.17 (d, J = 13.7 Hz, 1H), 1.93 (dd, J = 15.5, 7.2 Hz, 1H). ¹³C NMR (101 MHz, CDCl3) δ 209.53, 163.17, 141.57, 136.43, 136.36, 129.87, 128.37, 127.03, 125.08, 122.77, 118.94, 118.88, 118.45, 40.94, 28.91, 27.13, 26.47. HRMS (ESI): calcd for C₁₉H₁₉O₂ [M + H]: 279.1385, found: 279.1383.