13C NMR (125 MHz, DMSO‑d 6) δ 156.1, 152.4, 148.4, 147.6, 140.2, 136.4, 133.8, 133.5, 133.2, 133.0, 130.8, 129.4, 125.5, 123.4, 121.2, 119.0, 122.0, 122.0, 119.3, 113.5, 107.7, 89.4, 84.3, 83.0, 81.5, 44.7, 26.9, 25.0.