7.00 g (0.0316 mol) of N-(2-fluorobenzyl)-1-oxa-6-azaspiro[2,5]-octane and 5.50 g (0.0314 mol) of 5-bromo-2-hydroxy-pyridine were weighed and added into 40 mL of N,N-dimethylformamide, and then 0.53 g (0.004 mol) of potassium carbonate was added. The reaction was stirred and reacted at a bath temperature of about 80° C. for 1 day and the solvent was recovered under reduced pressure. Potassium carbonate aqueous solution was added to the residue and the mixture was extracted with dichloromethane twice, combined, washed with water and dried, and the solvent was recovered. The residue was crystallized with petroleum ether-ethyl acetate to obtain a colorless flake-like crystal, 4.20 g, yield 69.3%. 1H-NMR (CDCl3, ppm) δ: 7.413 (1H, s), 7.399 (1H, dd, J1=8.20 Hz, J2=2.80 Hz), 7.358 (1H, t×d, J1=7.28 Hz, J2=1.68 Hz), 7.229 (1H, m), 7.096 (1H, t×d, J1=7.56 Hz, J2=1.12 Hz), 7.021 (1H, hept→t, J1=9.80 Hz), 6.543 (1H, dd, J=8.12 Hz), 3.994 (2H, s), 3.848 (1H, s), 3.602 (2H, s), 2.699 (2H, dd, J1=7.56 Hz, J2=3.82 Hz), 2.46 (2H, t×d, J1=8.96 Hz, J2=2.52 Hz), 1.54-1.74 (4H, m). The product was heated and dissolved in ethanol-ethyl acetate, salified with HCl-EtOH while warm and naturally cooled to obtain a colorless fine granular crystal, which was dried under vacuum to obtain 4.60 g product. Melting point: 184-186° C.
