[NH2:1][C@H:2]1[CH2:7][CH2:6][C@H:5]([C:8]([OH:10])=[O:9])[CH2:4][CH2:3]1.[CH3:11][CH2:12]O.Cl>>[NH2:1][C@H:2]1[CH2:7][CH2:6][C@H:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][CH2:3]1A suspension of (trans)-4-aminocyclohexanecarboxylic acid (5 g, 34.9 mmol) in EtOH (100 mL, 1713 mmol) was treated with HCl (9.09 mL, 105 mmol) and the mixture was stirred at 60° C. overnight. The reaction mixture turned to clear solution. It was concentrated under reduced pressure and the residue was triturated with Et2O in CH3CN (50%) and the resulting white solid was collected. There was some product left in the filtrate so it was concentrated and triturated with Et2O in CH3CN (50%), the white solid was collected by filtration and combined with the white solid that was collected previously to provide 13A.HCl (5.25 g, 25.3 mmol, 72.4% yield). 1H NMR (400 MHz, CDCl3) δ ppm 4.06 (q, 2H, J=7.1 Hz); 3.01-3.15 (m, 1H); 1.34-2.31 (m, 9H); 1.18 (t, 3H, J=7.1 Hz).
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