13C NMR (150 MHz, D2O) δ 174.5, 154.9 (2C) 152.5, 152.2, 147.7, 147.5, 139.3, 138.5, 118.5, 118.2, 89.0, 86.8, 84.8, 81.7, 80.0, 73.9, 71.1, 68.9, 67.7, 60.3, 56.2, 55.3, 53.8, 52.5, 26.1.