Synthesis of N-BOC-6-bromohexylamine from 6-(BOC-amino)-1-hexanol General procedure: To 6-(BOC-amino)-1-hexanol (0.500 g, 2.82 mmol, 1 eq.) dissolved in a 1:1 dioxane/water mixture (12 mL) was added K2CO3 (1.870 g, 13.56 mmol, 4 eq.) and stirred for 10 min at room temperature. stirred for 10 minutes at room temperature. Subsequently, di-tert-butyl dicarbonate (0.7 mL, 3.39 mmol, 1.2 eq.) was added to the mixture and stirring was continued overnight. After completion of the reaction, the reaction mixture was diluted with EtOAc (12 mL) and the organic layer was separated. The organic layer was sequentially washed with 10% HCl (2 x 10 mL), dried with MgSO4 and then concentrated in vacuum. The product 0.570 g (2.62 mmol, 93% yield) was obtained, which could be used in the next step without further purification. Thin layer chromatography (TLC) showed an Rf value of 0.50 (silica gel, 60% EtOAc/Hex).1H NMR (400 MHz, CDCl3) δ: 4.51 (br s, 1H), 3.61 (t, J = 6.5 Hz, 2H), 3.09 (t, J = 6.7 Hz, 2H), 1.42 (s, 9H), 1.55-1.30 ( m, 8H) ppm.13C NMR (100 MHz, CDCl3) δ: 156.1, 79.0, 62.7, 40.4, 32.6, 30.1, 28.4, 26.4, 25.3 ppm.The NMR spectra were in agreement with the literature report [41].
Next, CBr4 (0.920 g, 2.76 mmol, 1 eq.) and PPh3 (0.720 g, 2.76 mmol, 1 eq.) were added to 6-(tert-butoxycarbonylamino)hexan-1-ol (0.600 g, 2.76 mmol, 1 eq.) dissolved in anhydrous dichloromethane (14 mL) and the reaction was carried out at 0 °C. The reaction mixture was slowly warmed up to room temperature over 2 hours. Upon completion of the reaction, the mixture was concentrated in vacuum and purified by column chromatography to afford the product 0.696 g (2.48 mmol, 90% yield). Thin layer chromatography (TLC) showed an Rf value of 0.57 (silica gel, 20% EtOAc/Hex).1H NMR (400 MHz, CDCl3) δ: 4.48 (br s, 1H), 3.66 (t, J = 6.8 Hz, 2H), 3.09 (t, J = 6.5 Hz, 2H), 1.88-1.82 (m, 2H), 1.47 ( s, 9H), 1.54-1.18 (m, 6H) ppm. 13C NMR (100 MHz, CDCl3) δ: 156.1, 62.9, 51.1, 32.8, 28.5, 26.4, 25.4 ppm. the NMR spectra were in agreement with the literature reports [42].
