Ammonium Chloride → Methyl [(2S)-2-(3,5-difluorophenyl)-2,5,5-trimethyl-6-oxopiperidin-1-yl]acetate

Participants

Reaction Steps

To a solution of (6S)-6-(3,5-difluorophenyl)-3,3,6-trimethylpiperidin-2-one (540. mg, 2.13 mmol) in THF (20 mL), chilled to 0° C. was added potassium hydride (approximately 86 mg, 2.13 mmol, as a 30% suspension in oil) under a constant stream of nitrogen. The reaction was allowed to stir for 30 minutes at which time methyl bromoacetate (391 mg, 2.56 mmol) was added at 0° C. An LCMS after one hour indicated that the reaction was incomplete, thus more potassium hydride was added (approximately 43 mg, 1.06 mmol, as a 30% suspension in oil) at 0° C. The reaction was sealed well and was stirred for an additional 16 hours, during which time the bath temperature warmed to ambient temperature. The reaction was judged to be 46% complete by LCMS analysis. The reaction was chilled to 0° C. and saturated aqueous ammonium chloride (5 mL) was added to quench the potassium hydride. To the reaction was added 1M aqueous HCl (5 mL) and the reaction was diluted with ethyl acetate. The organic layer was washed once with brine and then dried over sodium sulfate, filtered, and concentrated in vacuo to give a residue that was purified by silica gel chromatography, eluting with a gradient of EtOAc:Hexanes-10:90 to 75:25, to give the title compound. MS: m/z=326 (M+1).

Provenance & Evidence