Synthesis
A reaction mixture was prepared from methyl 1-cyanomethyl-cyclohexanecarboxylate (4.28 g, 23.6 mmol) and cobalt(II) chloride hexahydrate (2.81 g, 11.8 mmol) in a solvent mixture of THF (80 mL) and water (40 mL) at 0 °C. Subsequently, sodium borohydride (4.47 g, 0.118 mol) was added in batches and the reaction mixture was slowly warmed to room temperature and stirred under nitrogen protection for 48 hours. Upon completion of the reaction, the reaction was quenched by the addition of 28% ammonium hydroxide solution (3.1 mL) and filtered through Hyflo. The filtrate was concentrated under reduced pressure and the residue was diluted with minimal amounts of water and brine and then extracted three times with 3:1 chloroisopropanol. The organic layers were combined, dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with a dichloromethane solution of 0 to 10% methanol to give 2-azaspiro[4.5]decan-1-one 1.95 g (54% yield). Thin layer chromatography (TLC) Rf value was 0.46 (unfolding agent: 9/1 dichloromethane/methanol). Mass spectrometry (MS) showed a molecular ion peak m/z: 154 (M+).
