24424-99-5

52-52-8

35264-09-6

Cycloleucine (1.0 g, 7.74 mmol), triethylamine (Et3N, 5.4 mL, 38.7 mmol), 1 M aqueous NaOH (7.74 mL, 7.74 mmol) and acetonitrile (CH3CN, 10 mL) were added to a 250 mL round-bottom flask. The resulting clarified solution was cooled to 0 °C, followed by the slow addition of di-tert-butyl dicarbonate ((Boc)2O). The reaction mixture was gradually warmed to room temperature and stirred continuously for 4 h. A white precipitate was generated during the reaction. After completion of the reaction, the mixture was concentrated and the residue was dissolved in a solvent mixture of ethyl acetate (EtOAc) and water (1:1, 100 mL). The organic phase was separated and the aqueous phase was acidified with 10% HCl and then extracted three times with EtOAc. All organic phases were combined, washed with water and saturated saline in turn, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated to give 1-((tert-butoxycarbonyl)amino)cyclopentanecarboxylic acid as a white solid (1.29 g, 73% yield).