Sodium borohydride → cis-6-(3,5-Difluorophenyl)-4-hydroxy-3,3-dimethylpiperidin-2-one

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Reaction Steps

To a solution of 6-(3,5-difluorophenyl)-3,3-dimethylpiperidine-2,4-dione from Step A (20.18 g, 80 mmol) in THF (600 mL) and CH3OH (25 mL) at 0° C. was added NaBH4 (4.57 g, 121 mmol). After 2.5 h, the reaction mixture was quenched with H2O (200 mL) and concentrated in vacuo. The residue was partitioned between H2O (600 mL), saturated aqueous NaHCO3 (200 mL) and EtOAc (1 L). The organic layer was separated and the aqueous layer was extracted with EtOAc (600 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated in vacuo. The crude product was purified by silica gel chromatography, eluting with a gradient of CH2Cl2:CH3OH-100:0 to 88:12, to give the title compound, which contained approximately 20% of the corresponding trans-isomer. MS: m/z=256 (M+1).

Provenance & Evidence