Ammonium Chloride → tert-Butyl 4-(cyanomethylidene)piperidine-1-carboxylate

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Reaction Steps

Diethyl cyanomethylphosphonate (16 mL, 100 mmol) was dissolved in tetrahydrofuran (360 mL), and a solution of lithium hexamethyldisilazide in tetrahydrofuran (1 M, 100 mL, 100 mmol) and a solution of tert-butyl 4-oxopiperidine-1-carboxylate (18 g, 91 mmol) in tetrahydrofuran (36 mL) were added under a nitrogen atmosphere at −70° C., followed by stirring at the same temperature for 40 minutes. A saturated aqueous ammonium chloride solution was added to the reaction solution, followed by extraction with ethyl acetate, and the extract was washed with a saturated aqueous ammonium chloride solution. After the solvent was distilled off under reduced pressure, the resulting residue was purified by chromatography on a silica gel column (Moritex Corporation, elution solvent: hexane/ethyl acetate), and a fraction corresponding to the Rf value=0.41 (hexane/ethyl acetate=3/1) by thin layer chromatography was concentrated under reduced pressure to afford the title compound (22 g) as a white solid (quantitative yield).

Provenance & Evidence