[Synthesis]
First, trans-4-(aminomethyl)cyclohexane ethylcarboxylic acid hydrochloride was synthesized using trans-4-(aminomethyl)cyclohexanecarboxylic acid purchased from TCI (Japan) as starting material. Trans-4-(aminomethyl)cyclohexanecarboxylic acid (1.57 g, 10 mmol) was dissolved in 40 mL of ethanol at 0 °C with continuous stirring. Thionyl chloride (0.9 mL, 12 mmol) was slowly added dropwise to the reaction system, kept at low temperature and stirring was continued for 10 minutes. Subsequently, the reaction mixture was warmed to 70 °C and refluxed for 1 hour. After completion of the reaction, the mixture was cooled to room temperature. The solvent was thoroughly evaporated under reduced pressure and the resulting residue was washed twice with hexane (25 mL) to remove residual solvent. Finally, the product was dried under vacuum for 6 h to give a white solid trans-4-(aminomethyl)cyclohexane ethylcarboxylic acid hydrochloride in a yield of 2.13 g (96% yield). The product was characterized by 1H NMR (d6-DMSO): δ= 4.03 (q, J = 7.08,2H, OCH2CH3), 2.61 (m, 1H, H13), 2.21 (m, 1H, H10), 1.85 (m, 2H, H9), 1.27 (m, 4H, H12, H11), 1.16 (t, J = 7.06,3H. OCH2CH3), 0.96 (m, 4H, H12, H11). Elemental analysis results (C10H20ClNO2) Calculated values: C, 54.17; H, 9.09; N, 6.32. Measured values: C, 53.78; H, 8.91; N, 6.34. |