The general procedure for the synthesis of N-Boc-3-aminopropyl bromide from di-tert-butyl dicarbonate and 3-bromopropylamine hydrobromide is as follows: refer to Example 4, Synthesis of Boc-Aminopropyl Bromide: 1.222 g (5.58 mmol) of 3-bromopropylamine hydrobromide was dissolved in 20 mL of dichloromethane to which was added under cooling in an ice bath 0.778 mL (5.58 mmol) of triethylamine and 50 mL of dichloromethane. A solution of 1.214 g (5.56 mmol) of di-tert-butyl dicarbonate (Boc2O) was added slowly and dropwise over a period of 10 min, followed by stirring of the reaction mixture. After continued stirring at room temperature for 50 min, ethyl acetate was added to the reaction system and the organic phase was washed sequentially with 5% aqueous citric acid, water and saturated saline. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent to give 1.304 g of N-Boc-3-aminopropyl bromide in 98% yield. The structure of the product was confirmed by 1H-NMR. 1H-NMR (500 MHz, CDCl3) δ (ppm) = 1.44 (9H, s, Boc group), 2.05 (2H, quintet, -NHCH2CH2CH2Br), 3.28 (2H, quartet, -NHCH2CH2CH2Br), 3.44 ( 2H, triplet, -NHCH2CH2CH2Br), 4.64 (1H, s, NH).
