C([C:4]1[C:9]([CH3:10])=[CH:8][C:7]([CH:11]2[O:16][CH2:15][CH2:14][CH2:13][O:12]2)=[CH:6][C:5]=1[CH3:17])C=C.[OH2:18].[CH3:19][C:20]([CH3:22])=[O:21]>C(O)(C)(C)C.C(Cl)Cl.O=[Os](=O)(=O)=O>[O:12]1[CH2:13][CH2:14][CH2:15][O:16][CH:11]1[C:7]1[CH:8]=[C:9]([CH3:10])[C:4]([CH2:19][CH:20]([OH:21])[CH2:22][OH:18])=[C:5]([CH3:17])[CH:6]=1A solution of 2-(4-allyl-3,5-dimethyl-phenyl)-[1,3]dioxane (790 mg, 3.4 mmol) in acetone (10 mL) is treated with OsO4 (1 mL of a 2.5% solution in tert.butanol), NMO hydrate (551 mg, 4.08 mmol) and water (0.5 mL). The mixture is stirred at rt for 2.5 h before it is diluted with DCM, washed with 10% aq. citric acid solution (2×50 mL), dried over MgSO4, filtered and evaporated. The product is crystallized from DCM/heptane to give 3-(4-[1,3]dioxan-2-yl-2,6-dimethyl-phenyl)-propane-1,2-diol (335 mg) as a grey powder; 1H NMR (CDCl3): δ 7.15 (s, 2H), 5.42 8 s, 1H), 4.26 (dd, J=4.6, 10.6 Hz, 2H), 3.98 (dt, Jd=1.8 Hz, Jt=12.3 Hz, 2H), 3.92-3.81 (m, 2H), 3.66 (dd, J=2.9, 11.1 Hz, 1H), 3.55 (dd, J=7.0 11.1 Hz, 1H), 2.88 (dd, J=8.8, 14.1 Hz, 1H), 2.74 (dd, J=5.3, 13.5 Hz, 1H), 2.34 (s, 6H), 2.30-2.14 (m, 2H), 1.90 (s br, 2H).
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