13C NMR (150 MHz, DMSO‑d 6) δ 156.2, 156.0, 152.6, 152.5, 149.3, 149.0, 139.8, 139.7, 138.2, 131.1, 130.4, 127.8, 119.3, 119.16, 87.67, 86.3, 86.1, 82.4, 81.2, 72.4, 71.8, 69.0, 67.5, 61.5, 57.5, 55.8, 52.9.