13C NMR (125 MHz, DMSO‑d 6) δ 156.1, 156.0, 152.6, 152.5, 149.3, 148.9, 147.4, 140.1, 139.5, 139.5, 132.7, 131.6, 129.6, 124.3, 119.3, 119.3, 87.6, 86.2, 85.8, 81.8, 81.5, 72.3, 71.3, 68.8, 68.1, 61.4, 50.8, 48.1.