¹³C NMR (176 MHz, CDCl₃) δ 168.99 (s, 1C), 163.16 (d, J = 247.0 Hz, 1C), 151.29 (s, 1C), 147.61 (s, 1C), 138.80 (s, 1C), 136.37 (d, J = 7.6 Hz, 1C), 130.74 (d, J = 8.3 Hz, 1C), 125.23 (d, J = 2.9 Hz, 1C), 120.19 (s, 1C), 116.60 (d, J = 21.6 Hz, 1C), 114.79 (d, J = 21.0 Hz, 1C), 114.37 (s, 1C), 44.53 (s, 1C).