反应详情

Cyclobutanecarbonyl chloride (72.7 mg, 0.613 mmol) and NaOH (0.735 mL, 0.735 mmol) were dropped at the same time to a stirred solution of (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-aminopropanoic acid (200 mg, 0.613 mmol) in THF (1.5 mL) and NaOH (1N, 0.8 mL) at 0° C. The reaction mixture was allowed to stir at rt for 1 h at which time LC-MS showed the desired product peak. The reaction solution was acidified with 1N HCl and extracted with EtOAc (60 mL×1). The crude was purified via flash chromatography (ISCO, silica gel, 12 g column; flow rate 30 mL/min, 100% DCM to 20% MeOH/DCM). Fractions containing the desired product were combined and dried via centrifugal evaporation to provide the title compound (156 mg, 61%).