[CH2:1]([O:3][C:4](=[O:24])[CH2:5][O:6][C:7]1[CH:12]=[CH:11][C:10]([S:13][C:14]2[CH:19]=[CH:18][C:17]([CH:20]=[O:21])=[CH:16][C:15]=2[Cl:22])=[CH:9][C:8]=1[CH3:23])[CH3:2].CCO.[BH4-].[Na+].Cl>C1COCC1>[CH2:1]([O:3][C:4](=[O:24])[CH2:5][O:6][C:7]1[CH:12]=[CH:11][C:10]([S:13][C:14]2[CH:19]=[CH:18][C:17]([CH2:20][OH:21])=[CH:16][C:15]=2[Cl:22])=[CH:9][C:8]=1[CH3:23])[CH3:2]An oven-dried 500 mL round-bottomed flask was charged with compound 10.4 (34.9 g, 95.7 mmol), EtOH (175 mL) and THF (17.5 mL). Next, sodium borohydride (1.10 g, 29.1 mmol) was added in 3 portions at 0° C., and the reaction was vigorously stirred at 0° C. for 1 h. The reaction mixture was poured into 463 mL of 0.25 N HCl at 0° C. and the product was extracted with 3×200 mL of AcOEt. The combined organics were washed sequentially with 2×200 mL of water and 100 mL of brine, dried over Na2SO4, and concentrated to a yellow oil, which was then purified by flash chromatography (SiO2 gel 60 N, eluted with 20% AcOEt/hexane-30% AcOEt/hexane). The fractions containing only desired product were combined and concentrated to a slightly yellow oil (33.5 g). 1H NMR (400 MHz) (CDCl3) δ 7.37 (1H, d, J=1.5 Hz); 7.31-7.28 (2H, m); 7.05 (1H, dd, J=1.8, 8.2 Hz); 6.77 (1H, d, J=8.2 Hz); 6.72 (1H, d, J=8.3 Hz); 4.67 (2H, s); 4.61 (2H, d, J=5.9 Hz); 4.28 (2H, q, J=7.2 Hz); 2.29 (3H, s); 1.66 (1H, t, J=5.9 Hz); 1.31 (3H, t, J=7.2 Hz).
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