Reaction Steps
A solution of 210 (149 mg, 0.46 mmol) in dioxane (5 mL) under Ar was treated with DMAP (50 mg, 0.40 mmol), pyridine (0.37 mL, 4.6 mmol) and Ac2O (0.2 mL, 2.3 mmol) and stirred at 25° C. for 19 h. The reaction solution was quenched by the addition of 10% aqueous HCl (10 mL) and EtoAc (10 mL). The aqueous layer was removed and extracted with EtOAc (3×5 mL). The organic solutions were combined, washed with saturated aqueous NaCl (15 mL), dried (MgSO4), and concentrated under reduced pressure. Chromatography (SiO2, 15% EtOAc-hexane) afforded 211 (162 mg, 169 mg theoretical, 96%) as a pale yellow oil: 1H NMR (CDCl3, 400 MHz) δ8.33 (dd, 1H, J=1.6, 8.1 Hz, C8-H), 7.77 (dd, 1H, J=1.7, 7.5 Hz, C5-H), 7.52 (m, 5H, C6H5), 7.38 (m, 2H, C6 and C7-H), 7.20 (d, 1H, J=1.6 Hz, C4-H), 6.57 (d, 1H, J=1.6 Hz, C2-H), 5.25 (s, 2H, CH2Ph), 4.43 (dtd, 1H, J=1.9, 7.9, 24.8 Hz, C2'-H), 4.32 (dd, 1H, J=1.6, 1.6 Hz, C1'-H), 4.30 (m, 1H, C1'-H), 1.82 (s, 3H, CH3CO); 13C NMR (CDCl3, 100 MHz) δ170.0, 160.0, 157.1, 155.1, 139.4, 135.9, 133.8, 128.2, 127.7, 127.2, 127.1, 126.9, 125.7, 124.7, 121.9, 118.6, 105.0, 74.9 (dd, J=75.2, 91.6 Hz), 69.8, 41.8 (d, J=28 Hz), 22.0; 19F NMR (CDCl3, 376 MHz) δ-87.0 (d, J=40.0 Hz), -89.1 (dd, J=24.8, 40.0 Hz); IR (film) vmax 2928, 1745, 1660, 1413 cm-1 ; FABHRMS (NBA-NaI) m/z 368.1740 (M+H+, C22H19F2NO requires 368.1470).
