¹H NMR (400 MHz, CDCl₃) δ 10.40 (s, 1H), 9.30 (d, J = 8.8 Hz, 1H), 7.96 (d, J = 7.2 Hz, 1H), 7.84 (s, 1H), 7.63 (d, J = 8.7 Hz, 1H), 7.54 (d, J = 7.2 Hz, 1H), 7.45 (d, J = 7.5 Hz, 2H), 7.40 (d, J = 7.4 Hz, 2H), 3.03 (dq, J = 13.9, 7.0 Hz, 2H), 1.37 (d, J = 6.8 Hz, 6H), 1.28 (d, J = 6.7 Hz, 6H). ¹³C NMR (101 MHz, CDCl₃) δ 193.40, 148.77, 147.42, 147.23, 137.44, 135.47, 132.30, 130.33, 129.78, 129.74, 128.17, 126.52, 126.23, 125.09, 123.45, 34.41, 33.96, 24.02, 23.85.