[CH2:1]([CH:4]1[CH2:8][CH:7]([O:9][CH2:10][C:11]2[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=2)[CH2:6][O:5]1)[CH:2]=C.I([O-])(=O)(=O)=[O:18].[Na+].C(OCC)(=O)C.CCCCCC>C1COCC1.O.CCOCC.[Os](=O)(=O)(=O)=O>[CH2:10]([O:9][CH:7]1[CH2:6][O:5][CH:4]([CH2:1][CH:2]=[O:18])[CH2:8]1)[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1To a stirred solution of 2-allyl-4-(benzyloxy)tetrahydrofuran (3.1 g, 14.20 mmol) in THF (100 mL) and water (100 mL) was added osmium tetroxide (2 mL, 0.327 mmol) at room temperature. After a few minutes, sodium periodate (7.59 g, 35.5 mmol) was added in small portions over 15 min. After 20 h, the reaction mixture was diluted with ether (200 mL), filtered and the filtrate washed with water (2×50 mL) followed by brine (50 mL), then dried (Na2SO4), filtered and concentrated to give a gray oil. Flash column chromatography on a silica gel column using 15-30% ethyl acetate/hexane (5% increment) gave 2-(4-(benzyloxy)tetrahydrofuran-2-yl)acetaldehyde (2.4624 g, 11.18 mmol, 79% yield) as a colorless liquid consisting of a ˜4:1 mixture of diastereomers. 1H NMR (500 MHz, CDCl3) δ: 9.81 (0.8 H, s), 9.77 (0.2 H, s), 7.23-7.37 (5 H, m), 4.48 (1.6 H, s), 4.41 (0.4 H, s), 4.29-4.31 (1 H, m), 4.23-4.20 (0.8 H, m), 4.12-4.09 (0.2 H, m), 4.04-4.06 (0.8 H, m), 3.90-3.94 (0.2 H, m), 3.73 (0.8 H, dd, J=9.9, 4.7 Hz), 3.64 (0.2 H, dd, J=9.9, 4.7 Hz), 2.82-2.94 (1 H, m), 2.60-2.73 (1 H, m), 2.25-2.39 (1 H, m), 1.77 (0.8 H, m), 1.59-1.69 (0.2 H, m). LCMS (M+H) calcd for C13H17O3: 221.12; found: 221.05.
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