(2S,5R)-5-(4-((2-fluorobenzyl)oxy)phenyl)pyrrolidine-2-carboxamide (5.46 g, 17.37 mmol) was used as a raw material, which was dissolved in ethyl acetate (140 mL), stirred for 30 min and filtered. To the filtrate was added a dioxane solution (6.51 mL, 26.05 mmol) in 4 M HCl and the reaction was stirred at room temperature for 20 minutes, followed by cooling in an ice bath for 15 minutes. The resulting solid was collected by filtration, washed with cold ethyl acetate (2 x 20 mL) and dried under vacuum first at 35 °C overnight and then at 50 °C for 2 h to give an off-white solid product (E1, 5.87 g, 96% yield).LC-MS showed MH+ = 315 (corresponding to molecular formula C18H19FN2O2).1H NMR (d6-DMSO) data were as follows: δ 1.95-2.20 (2H, m), 2.30 (2H, m), 3.35 (1H, s), 4.30 (1H, m), 4.61 (1H, m), 5.18 (2H, s), 7.10 (2H, d, J = 9 Hz), 7.18-7.30 (2H, m), 7.40 (1H, m), 7.47 (2H, d, J = 9 Hz), 7.56 (1H, s), 7.72 (1H, s), 8.07 (1H, s), 10.60 (1H, br s).
