Oxalyl chloride → (S)-2-(((S)-1-(((9H-fluoren-9-yl)methoxy)carbonyl)pyrrolidine-2-carbonyl)oxy)propanoic acid

Participants

Reaction Conditions

Reaction Steps

Oxalyl chloride (2.34 mL, 26.7 mmol) was added dropwise to a solution of (S)-1-(((9H-fluoren-9-yl)methoxy)carbonyl)pyrrolidine-2-carboxylic acid (Fmoc-Pro-OH) (6.00 g, 17.8 mmol) and N,N-dimethylformamide (69 μL, 0.889 mmol) in methylene chloride (71 mL) with stirring at 0° C. under a nitrogen atmosphere, and the reaction mixture was then stirred at room temperature for 1 hour. The reaction solution was concentrated under reduced pressure, the resulting residue was mixed with methylene chloride (71 mL), N-ethyldiisopropylamine (DIPEA) (46.6 mL, 267 mmol) and L-(+)-lactic acid (24.0 g, 267 mmol) at 0° C., and the reaction mixture was stirred at room temperature for 2 hours. The reaction solution was washed with 1 N hydrochloric acid twice and a saturated aqueous sodium chloride solution twice, dried over sodium sulfate and then concentrated under reduced pressure. The resulting residue was purified by reverse-phase silica gel column chromatography (0.1% aqueous formic acid solution/0.1% formic acid-acetonitrile solution) to afford (S)-2-(((S)-1-(((9H-fluoren-9-yl)methoxy)carbonyl)pyrrolidine-2-carbonyl)oxy)propanoic acid (Fmoc-Pro-Lac-OH) (Compound SP633) (5.2 g, 12.7 mmol, 71%).

Provenance & Evidence