General procedure for the synthesis of tert-butyl N-(3-hydroxypropyl)carbamate:
1. an anhydrous dichloromethane (DCM, 50 mL) solution of di-tert-butyl dicarbonate ((Boc)2O, 25.0 g, 114.5 mmol) was added slowly and dropwise under nitrogen protection to an anhydrous DCM solution (100 mL) of 3-amino-1-propanol (41, 7.8 g, 104.5 mmol) under stirring.
2. The reaction mixture was stirred at room temperature for 12 h. The progress of the reaction was monitored by thin layer chromatography (TLC, 50% petroleum ether/ethyl acetate) to confirm complete consumption of the feedstock.
3. Upon completion of the reaction, the reaction solution was diluted with ether (Et2O, 150 mL) and washed sequentially with phosphate buffer (0.5 M, pH 5.4, 2 × 70 mL), saturated aqueous sodium bicarbonate (70 mL) and brine (2 × 70 mL).
4. The organic phase was dried with anhydrous magnesium sulfate (MgSO4), filtered and the excess solvent was removed by evaporation under reduced pressure to afford the colorless viscous oily product tert-butyl N-(3-hydroxypropyl)carbamate (42, 18.3 g, 100% yield).
Product characterization data:
1H NMR (270 MHz, CDCl3): δ 1.44 (s, 9H, CH3), 1.67 (m, 2H, H2'), 3.26 (q, 2H, J = 6.23 Hz, H3'), 3.65 (dd, 2H, J = 5.86, 5.68 Hz, H1'), 3.78 (dt, 1H, J = 6.04, 5.87 Hz, OH), 5.18 (br, 1H, NH).
13C NMR (67.8 MHz, CDCl3): δ 28.4 (CH3), 32.6 (C2'), 37.1 (C3'), 59.3 (C1'), 79.4 (Cquater), 157.1 (CO); MS (E/I) m/l, 1H, J = 6.04, 5.87 Hz, OH, 5.18 (br, 1H, NH).
MS (E/I) m/z (relative strength): 176 (M+, 30), 120 (100), 119 (31), 102 (49), 83 (33), 76 (67), 74 (36).
HRMS (E/I) Calculated value C8H17O3N: m/e 175.1200, measured value m/e 175.1208; IR (Nujol) ν
IR (Nujol) ν (cm-1): 3355, 2976, 2936, 2878, 1810, 1694, 1531, 1455, 1392, 1366, 1278, 1253, 1173, 1072, 996, 914, 870, 781, 752, 638.
