109-07-9

501-53-1

84477-85-0

Example 1: 5.00 g (0.0499 mol) of racemic 2-methylpiperazine was added to a 100 mL four-necked flask and dissolved in 44 g of 1-butanol (0.05 wt% in water). The solution was cooled to 0°C and 8.47 g of benzyl chloroformate (0.0489 mol, 98.5% purity as determined by HPLC, equivalent to 0.98 equivalents) was added slowly dropwise over a temperature range of 0 to 8°C. After the dropwise addition, the reaction mixture was stirred at 0 to 5 °C for 2 hours. During this time, a sample was taken and analyzed by HPLC using the internal standard method (internal standard: anisole), and the yield of 1-Benzyloxycarbonyl-3-methylpiperazine was measured to be 83.9% (based on 2-methylpiperazine). Subsequently, the reaction mixture was continued to be stirred at room temperature for 12 hours and analyzed again and the yield was increased to 85.1%. Example 3: The reaction conditions were the same as in Example 1 , with the difference that the amount of benzyl chloroformate was increased to 10.1 g (0.0597 mol, 1.17 eq.). After 2 hours of reaction at 0 to 5 °C, HPLC analysis showed 93.8% yield of 1 -benzyloxycarbonyl-3-methylpiperazine (based on 2-methylpiperazine). The yield was further increased to 95.1% after continued stirring at room temperature for 12 hours.