Sodium borohydride → 2,2-Difluoro-2-(pyridin-2-YL)ethanol

関与物質

反応手順

To a stirred solution of 19.5 g (97 mmol) of ethyl difluoro-2-pyridylacetate I-1-2 in 200 mL of absolute ethanol at 0° C. was added 4.42 g (116 mmol) of sodium borohydride in small portions. After 30 min, the reaction was quenched by the addition of 50 mL of sat. NH4Cl. The reaction mixture was concentrated at reduced pressure and the residue partitioned between 500 mL of ethyl acetate and sat. NaHCO3. The organic layer was washed with water, brine, and dried over Na2SO4 and concentrated at reduced pressure to give a brown oil that was purified on SiO2 (10×17 cm) using 1:1 EtOAc-hexane. After re-chromatographing the mixed fractions, all clean fractions were combined and concentrated at reduced pressure, giving I-1-3 as a beige crystalline solid: 1H NMR (CDCl3) δ3.6 (t, 1H), 4.17-4.3 (m, 2H), 7.4-7.45 (m, 1H), 7.73 (d, 1H), 7.84-7.91 (m, 1H), 8.61 (d, 1H).

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