13C NMR (150 MHz, D2O) δ 174.5, 154.9 (2C), 152.5, 152.3, 147.7, 147.5, 139.3, 138.5, 118.6, 118.3, 89.0, 86.9, 84.8, 81.8, 80.1, 73.9, 71.1, 69.0, 67.8, 60.3, 56.2, 55.3, 53.8, 52.5, 26.1.