[F:1][CH:2]([F:13])[O:3][C:4]1[CH:9]=[CH:8][C:7]([CH2:10][CH:11]=[O:12])=[CH:6][CH:5]=1.[BH4-].[Na+]>C(O)C>[F:1][CH:2]([F:13])[O:3][C:4]1[CH:5]=[CH:6][C:7]([CH2:10][CH2:11][OH:12])=[CH:8][CH:9]=1A solution of (4-difluoromethoxyphenyl)-acetaldehyde 1.22 g, 6 mmol; from step (ii) above) in ethanol (20 mL) was cooled to 0° C. Sodium borohydride (0.27 g, 7.2 mmol) was added and the resulting reaction mixture was stirred at 0° C. for 2 h and then at room temperature for 16 h. After concentration under reduced pressure, the residue was diluted with diethylether (50 mL) and 1 M HCl (50 mL). The phases were separated and the organic phase was washed with water (50 mL) and brine (50 mL), dried over Na2SO4, and concentrated in vacuo. The crude product was purified by two times repeated chromatography on silica gel. (Horizon™, flash system from Biotage™. Column: Flash 40+M, 40×150 mm. Eluent: Gradients from 25 to 40% ethyl acetate in heptane. Concentration in vacuo afforded 0.62 g (50%) of the sub-title compound as a light yellow oil.
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