Citric Acid → 4-[2-(5-Bromo-2-chloropyridin-4-yl)-1-hydroxy-ethyl]piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

Sodium borohydride (240 mg) is added to an ice-cooled solution of 4-[2-(5-bromo-2-chloro-pyridin-4-yl)-acetyl]-piperidine-1-carboxylic acid tert-butyl ester (1.65 g) in a mixture of tetrahydrofuran (40 mL) and water (10 mL). The resulting mixture is stirred for 0.5 h at room temperature. 2 N Aqueous citric acid is added and the mixture is extracted with ethyl acetate. The combined extracts are washed with aqueous NaHCO3 solution and brine, dried over MgSO4, and concentrated in vacuo. The residue is chromatographed on silica gel (cyclohexane/ethyl acetate 65:35) to give the title compound. LC (method 3): tR=1.48 min; Mass spectrum (ESI+): m/z=419, 421 [M+H]+.

Provenance & Evidence