A mixture of N2-cyclopropyl-4-fluorobenzene-1,2-diamine (0.724 g, 4.4 mmol), (S)-2-tertbutoxycarbonylaminopropionic acid (0.91 g, 4.8 mmol), HOAt (0.65 g, 4.8 mmol), 4-methylmorpholine (1.1 mL, 9.7 mmol) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.92 g, 4.8 mmol) in DCM (15 mL) was stirred at RT for 18 h. The reaction mixture was partitioned between DCM and a saturated aqueous solution of NaHCO3. The organic fraction was washed with brine, dried (MgSO4), concentrated in vacuo and the resulting residue purified by column chromatography (Si—PCC, gradient 0-30% EtOAc in cyclohexane) to afford [(S)-1-(2-cyclopropylamino-4-fluorophenylcarbamoyl)ethyl]carbamic acid tert-butyl ester as a brown oil (1.07 g, 72%). LCMS (Method B): RT 3.40 min [M+H]+ 338.2. 110180243
