(1S,4S)-2-Boc-2,5-diazabicyclo[2.2.1]heptane

113451-54-0

113451-59-5

Methylsulfonate 17 (1.2 g, 3.78 mmol) was used as raw material, which was suspended in anhydrous THF (38 mL), triphenylphosphine (1.48 g, 5.66 mmol) was added, and the reaction was stirred at room temperature for 2 hours. Subsequently, H2O (0.5 mL) was added and stirring was continued for 18 hours. Upon completion of the reaction, the solvent was removed under reduced pressure and the residue was suspended in 1 M hydrochloric acid (150 mL) and extracted with CH2Cl2 (2 x 70 mL). The aqueous layer was adjusted to pH 14 with base and then extracted with CH2Cl2 (3 × 70 mL). The organic phases were combined, washed with brine (100 mL), dried over anhydrous MgSO4 and concentrated under reduced pressure. Purification by rapid chromatography on silica gel with the eluent CH2Cl2-methanol-ammonia (90:9:1) afforded the target product amine 18 (0.52 g, 2.62 mmol, 71% yield) as a colorless solid. The product characterization data were as follows: melting point 76.8-77.9 °C; specific spin [α]D -47.6 (c 1.0, CHCl3); IR spectra (νmax/cm-1) 2975, 1688, 1408, 1170; 1H NMR (500 MHz, CDCl3) δ 4.43 (0.5H, s), 4.30 (0.5H, s), 3.69 (1H, s), 3.38-3.32 (1H, m), 3.19-3.13 (1H, m), 3.06-2.97 (2H, m), 1.75-1.65 (2H, m), 1.45-1.43 (9H, m); 13C NMR (125 MHz, CDCl3) δ 154.6, 154.3, 79.6, 79.5, 57.3, 56.6, 56.5, 56.3, 56.1, 52.8, 52.7, 37.2, 37.0, 28.66; mass spectra (APCI) m/z 199 ([M+H]+, 100).