Triethylamine → (2S,4R)-4-Hydroxypyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester

To an aqueous solution (40 ml) of L-hydroxyproline methyl ester hydrochloride (8.2 g, 45.2 mmol), triethylamine (7.54 ml, 54.2 mmol) was added at room temperature, and then a solution of 2-(tert-butoxycarbonylthio)-4,6-dimethylpyrimidine (10.8 g, 45 mmol) in dioxane (80 ml) was added thereto. The reaction solution was stirred at room temperature for 1.5 hours, and then dioxane was distilled off under reduced pressure. The residue was extracted with ethyl acetate (250 ml). The organic layer was washed sequentially with a 0.1 N sodium hydroxide aqueous solution, dilute hydrochloric acid, water and a saturated sodium chloride aqueous solution and then dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (Wakogel™ C-300, 5% methanol-methylene chloride) to obtain N-tert-butoxycarbonyl-L-hydroxyproline methyl ester (9.3 g, yield: 84%).

1. distillationdioxane was distilled off under reduced pressure
2. extractionThe residue was extracted with ethyl acetate (250 ml)
3. washThe organic layer was washed sequentially with a 0.1 N sodium hydroxide aqueous solution, dilute hydrochloric acid, water
4. dry with materiala saturated sodium chloride aqueous solution and then dried over anhydrous magnesium sulfate
5. concentrationconcentrated under reduced pressure

ORD record

ord-faf2c4596c8b4c35abc322ef49f06d14

Source dataset

uspto-grants-1994_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05374720