Di-2-pyridyl Carbonate

Experimental procedure: To a solution of N-Cbz-L-leucine (144.5 mg, 0.54 mmol) in dichloromethane (1.5 mL) are successively added di-2-pyridyl carbonate (117 mg, 0.54 mmol) and DMAP (5.3 mg, 0.043 mmol). After the reaction mixture has been stirred for 2 h under an argon atmosphere, glycine ethyl ester hydrochloride (67 mg, 0.48 mmol) and a solution of trimethylamine (50 mg, 0.50 mmol) in dichloromethane (1.5 mL) are successively added to it. This mixture is stirred for 2 h at room temperature and then the solvent is evaporated. The resulting mixture is purified by preparative TLC to afford 1 (164 mg, 97% yield) as a white solid.