Benzaldehyde → (1S,2S)-N-benzylcyclohexane-1,2-diamine

Benzaldehyde (3.05 mL, 30.0 mmol) was added to a methanol (300 mL) solution of (1S,2S)-cyclohexane-1,2-diamine (3.43 g, 30.0 mmol) with stirring at room temperature, and the mixture was stirred overnight at the same temperature. The reaction mixture was cooled to 0° C. Sodium borohydride (2.27 g, 60.0 mmol) was added thereto, and the mixture was stirred at 0° C. for 2 hours. To the reaction mixture, water (30 mL) was added, and the product was extracted twice with methylene chloride (50 mL). The organic layers were combined and dried over magnesium sulfate, and the solvent was then distilled off under reduced pressure. The obtained residue was purified by basic silica gel column chromatography (ethyl acetate/hexane) to obtain (1S,2S)-N-benzylcyclohexane-1,2-diamine (cas no. 207450-11-1) (2.95 g, yield: 48%) in a pale yellow oil form.