Isolated yield: 87% (320 mg, yellow solid). To a stirring solution of piperidin-4-one hydrochloride hydrate (921.6 mg, 6 mmol, 1.2 eq.) in 5 ml CH2Cl2 triethylamine (1.3 ml, 10.0 mmol, 2 eq.) was added. The reaction mixture was stirred continuously for 5 minutes. After that, (1S,2R,5R)-2-isopropyl-5-methylcyclohexyl carbonochloridate (1.1 g, 5 mmol, 1 eq.) as added in portions to the reaction mixture over a period of 5 minutes and the resulting solution was stirred overnight at room temperature. After completion of the reaction (monitored by TLC), the mixture was quenched with a 1N HCl and extracted with CH2Cl2 (2 x 5 mL). The combined organic layers were then washed with water