1-(3-Pyridyl)-4-tert-butoxycarbonylhomopiperazine (0.91 g, 3.3 mmol) was used as a raw material, which was dissolved in dichloromethane (30 mL), trifluoroacetic acid (7.5 g, 66 mmol) was added, and the reaction was stirred for 15 hours at room temperature. After completion of the reaction, the solvent was removed by evaporation under reduced pressure. The residue was neutralized by adding aqueous sodium hydroxide (30 mL, 4 M). The aqueous phase was extracted with dichloromethane (30 mL x 2) and the organic phases were combined to isolate the target product, 1-pyridine-3-1,4-diazepane, as an oil in a yield of 0.50 g in 85% yield. The product was dissolved in a mixed solvent of diethyl ether and methanol (9:1 v/v) and fumaric acid was added to saturation to give the corresponding fumarate salt. The melting point was determined to be 172.1-172.9 °C.
