GENERAL STEPS: Preparation Example 1 Synthesis of tert-butyl-N-(3-aminopropyl)-N-methylcarbamate (2). N-methyl-1,3-propanediamine (1) (3.26 g, 37.03 mmol) was dissolved in methanol (100 ml), and a 35% hydrochloric acid solution was slowly added at 0 °C, followed by stirring. The reaction solution was stirred at room temperature for 30 min, then cooled to -10 °C and di-tert-butyl dicarbonate (10.51 g, 48.14 mmol) was slowly added. After completion of the reaction, the reaction mixture was concentrated under reduced pressure and alkalized with 10% aqueous sodium hydroxide solution. The alkalized solution was extracted with dichloromethane and the organic phase was dried with anhydrous magnesium sulfate. The dried organic phase was concentrated under reduced pressure and the residue was purified by silica gel column chromatography (eluent ratio: dichloromethane: methanol: ammonia = 100:9:1, v/v/v) to give tert-butyl N-(3-aminopropyl)-N-methylcarbamate (2). Yield: 3.03 g (43%).1H NMR (400 MHz, CDCl3) δ 3.29 (2H, br, -CH2-NH2), 2.83 (3H, s, -N-CH3), 2.69 (2H, t, J = 6Hz, -N-CH2-CH2-), 1.64 (2H, m, -CH2-CH2-CH2-). 1.46 (9H, s, (CH3)3C-O-CO-), 1.38 (2H, s, -CH2-CH2-NH2).
