B#B.[CH3:3][S:4]([O:7][CH2:8][CH2:9][CH2:10][C:11]1([CH3:21])[CH:17]2[O:18][C:14]([CH:19]=[CH2:20])([CH2:15][CH2:16]2)[CH2:13][O:12]1)(=[O:6])=[O:5].[OH-:22].[Na+].OO>O1CCCC1.O>[CH3:3][S:4]([O:7][CH2:8][CH2:9][CH2:10][C:11]1([CH3:21])[CH:17]2[O:18][C:14]([CH2:19][CH2:20][OH:22])([CH2:15][CH2:16]2)[CH2:13][O:12]1)(=[O:5])=[O:6]A mixture of diborane in tetrahydrofuran (1 ml, 1 mM) is added slowly to a mixture of (1RS,4SR,5RS)-4-(3-methanesulfonyloxypropyl)-4-methyl-1-vinyl-3,8-dioxabicyclo[3.2.1]octane (350 mg, 1.2 mM) and tetrahydrofuran (5 ml) at 0° C. under nitrogen and stirred for thirty minutes. The resulting mixture is allowed to warm to room temperature and stirred for an additional two hours. The mixture is cooled to 0° C. and 3 N sodium hydroxide (0.3 ml) is added followed by the addition of 30% hydrogen peroxide (0.3 ml). The resulting mixture is allowed to warm to room temperature and stirred for 2.5 hours. The mixture is then treated with water (10 ml) and extracted with ether (5×20 ml). The combined organic phases are dried (Na2SO4) and the solvent is removed in vacuo. The residue is purified by column chromatography on silica gel (30 g) with ether to give (1RS,4SR,5RS)-4-(3-methanesulfonyloxypropyl)-4-methyl-3,8-dioxabicyclo[3.2.1]octane-1-ethanol (275 mg, 80%) as a colorless oil.
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