benzyl piperidine-2-carboxylate;hydrochloride

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Boc-L-Ile-OH ½ H2O (3.92 g, 16.8 mmol), H-D,L-Pip-OBzl HCl (3.57 g, 12 mmol) and HATU (7.75 g, 18 mmol) were dissolved in DMF (15 ml), mixed with Et3N (4.76 ml, 30 mmol) under ice cooling, and then stirred overnight. The reaction mixture was concentrated, extracted with ethyl acetate (120 ml), and washed twice with 10% citric acid, 4% NaHCO3 and then brine, respectively. After drying over magnesium sulfate, ethyl acetate was distilled off. The residue was vacuum dried and purified by flash chromatography (3.5×20 cm) with CHCl3/MeOH (99:1) to yield Boc-L-Ile-D,L-Pip-OBzl (5.90 g, 13.8 mmol; yield 97%) as an oil. The reaction mixture was concentrated extracted with ethyl acetate (120 ml) washed twice with 10% citric acid, 4% NaHCO3 After drying over magnesium sulfate, ethyl acetate was distilled off dried purified by flash chromatography (3.5×20 cm) with CHCl3/MeOH (99:1)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Boc-L-Ile-OH ½ H2O (3.92 g, 16.8 mmol), H-D,L-Pip-OBzl HCl (3.57 g, 12 mmol) and HATU (7.75 g, 18 mmol) were dissolved in DMF (15 ml), mixed with Et3N (4.76 ml, 30 mmol) under ice cooling, and then stirred overnight. The reaction mixture was concentrated, extracted with ethyl acetate (120 ml), and washed twice with 10% citric acid, 4% NaHCO3 and then brine, respectively. After drying over magnesium sulfate, ethyl acetate was distilled off. The residue was vacuum dried and purified by flash chromatography (3.5×20 cm) with CHCl3/MeOH (99:1) to yield Boc-L-Ile-D,L-Pip-OBzl (5.90 g, 13.8 mmol; yield 97%) as an oil. The reaction mixture was concentrated extracted with ethyl acetate (120 ml) washed twice with 10% citric acid, 4% NaHCO3 After drying over magnesium sulfate, ethyl acetate was distilled off dried purified by flash chromatography (3.5×20 cm) with CHCl3/MeOH (99:1)