Ethanolamine → [(R)-1-(2-hydroxy-ethylcarbamoyl)-ethyl]-carbamic acid tert-butyl ester

In a round-bottomed flask, Boc-D-alanine (1.0 g, 5.29 mmol was dissolved in THF (40 ml) and 1,1′-carbonyldiimidazole (1.03 g, 6.34 mmol) was added. The reaction mixture was stirred at 60° C. for 45 min then cooled to room temperature and ethanolamine (3.2 ml, 52.9 mmol) was added. The reaction mixture was stirred at room temperature overnight then quenched with 1 M aqueous HCl (15 ml) and extracted with dichloromethane. The organic layer was washed with 1 M aqueous HCl, water and brine. The aqueous layers were back-extracted with dichloromethane (2×). The organic layers were combined, dried over sodium sulfate, filtered and concentrated to afford 1.11 g (90%) of [(R)-1-(2-hydroxy-ethylcarbamoyl)-ethyl]-carbamic acid tert-butyl ester as a colorless oil.