3,3-Dichloro-5,5-dimethylpiperidin-2-one → 3-Chloro-5,5-dimethylpiperidin-2-one

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Reaction Steps

To 40.8 g (0.21 mol) of 3,3-dichloro-5,5-dimethyl-2-piperidone dissolved in 410 mL of AcOH was added 10% Pd/C (50% wet, 6.2 g) and NaOAc-3H2O (62.4 g, 0.46 mol) and the mixture was hydrogenated at 300 kPa for 20 min. The pressure of hydrogen was adjusted at 300 kPa every 5 min. The catalyst was removed by filtration and the filtrate concentrated under reduced pressure. CHCl3 (400 mL) and water (300 mL) were added to the residue and the aqueous layer was neutralized with 4 mol/L NaOH. The mixture was separated and the aqueous layer was extracted with CHCl3 (5×300 mL) and the organic layer was dried (MgSO4) and filtered. The filtrate was concentrated under reduced pressure. The residue was applied to silica-gel column chromatography, and then the column was eluted with hexane-AcOEt (1:1). The titled compound was obtained as a white solid (20.4 g, 59.9%). (J. Med. Chem., 20, 1176 (1977))

Provenance & Evidence