A mixture of N2-(trans-3-benzyloxycyclobutyl)-4-fluoro-benzene-1,2-diamine (1.73 g, 2.55 mmol), (S)-2-tertbutoxycarbonylaminopropionic acid (0.54 g, 2.81 mmol) and HOAt (0.38 g, 2.81 mmol) in DCM (20 mL) were cooled to 0° C. under nitrogen atmosphere. To this mixture N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (0.54 g, 2.81 mmol) was added portion wise and the reaction mixture was stirred at RT for 1 h. The reaction mixture allowed to warm to RT then partitioned between DCM (30 mL) and 10% aqueous citric acid (20 mL). The organic layer was washed with brine (20 mL), dried (MgSO4) and concentrated in vacuo and the resulting residue purified by column chromatography (Si—PCC, gradient 0-50% EtOAc in cyclohexane) to afford the title compound as a off-white gum, which solidified on standing (0.88 g, 75%). NMR: 328289. LCMS (Method B): RT 3.85 min [M+H]+ 458.
