In a round-bottom flask, 2-chloroethylamine hydrochloride (2 g, 17.0 mmol) and triethylamine (Et3N, 2.37 mL, 11.0 mmol) were dissolved in anhydrous dichloromethane (CH2Cl2, 24 mL). Di-tert-butyl dicarbonate (Boc2O, 3.6 mL, 15.3 mmol) was slowly added at 0 °C under the protection of nitrogen (N2). The reaction mixture was stirred at room temperature for 4 hours. Upon completion of the reaction, the mixture was washed sequentially with water (H2O) and brine, dried over anhydrous sodium sulfate (Na2SO4), filtered, and concentrated under reduced pressure to afford N-Boc-2-chloroethylamine as a dark liquid in a yield of 2.91 g (16.21 mmol, 99% yield), which was used directly in the next step of the reaction. The product was confirmed by infrared spectroscopy (IR, pure): 3347, 2924, 2854, 2361, 2342, 1725, 1709, 1503, 1462 cm-1. nuclear magnetic resonance hydrogen spectrum (1H NMR, 400 MHz, CDCl3): δ = 1.18 [s, 9H, C(CH3)3], 3.36-3.48 (m, 2H. CH2NH), 3.49-3.63 (m, 2H, ClCH2), 4.93 (br s, 1H, NHCO). Nuclear magnetic resonance carbon spectrum (13C NMR, 100 MHz, CDCl3): δ = 28.2 [C(CH3)3], 32.8 (CH2NH), 45.7 (CH2Cl), 79.8 [C(CH3)3], 155.8 (C=O). Elemental analysis (C7H14ClNO2) calculated values: C, 46.80; H, 7.86; N, 7.80. measured values: C, 46.91; H, 7.89; N, 7.74.
