[Si:1]([O:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][C:16]#[C:17][C:18]1(O)[C:27]2[C:22](=[CH:23][C:24]([O:28][CH3:29])=[CH:25][CH:26]=2)[S:21][CH2:20][C:19]1([C:31]1[CH:36]=[CH:35][C:34]([O:37][CH3:38])=[CH:33][CH:32]=1)[CH3:30])([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2].C([BH3-])#N.[Na+].O>ClCCCl.[I-].[Zn+2].[I-]>[Si:1]([O:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][C:16]#[C:17][CH:18]1[C:27]2[C:22](=[CH:23][C:24]([O:28][CH3:29])=[CH:25][CH:26]=2)[S:21][CH2:20][C:19]1([C:31]1[CH:36]=[CH:35][C:34]([O:37][CH3:38])=[CH:33][CH:32]=1)[CH3:30])([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:2])[CH3:3]To a solution of 4-[9-(t-butyldimethylsilyloxy)-1-nonynyl]-4-hydroxy-7-methoxy-3-(4-methoxyphenyl)-3-methylthiochroman (5.40 g, 9.49 mmol) in 1,2-dichloroethane (150 ml) were added zinc iodide (4.54 g, 14.23 mmol) and sodium cyanoborohydride (4.47 g, 71.17 mmol), which was then stirred at room temperature for 12 hours. After the reaction was completed, water was added to the reaction mixture, and the resulting mixture was extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was subjected to flash chromatography on silica gel (n-hexane:ethyl acetate=9:1) to give the title compound (2.64 g, yield 50%, 3RS/4RS:3RS/4SR=6:1) as a colorless oil.
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