¹³C NMR (176 MHz, DMSO) δ 162.35 (s, 1C), 141.13 (s, 1C), 140.02 (s, 1C), 138.24 (s, 1C), 128.25 (s, 1C), 127.33 (s, 1C), 126.68 (s, 1C), 126.52 (s, 1C), 122.06 (s, 1C), 121.60 (s, 1C), 121.56 (s, 1C), 110.72 (s, 1C), 41.89 (s, 1C).