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 0.1N 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 0.1N 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-ead1a63d66984b4b9c3a5e39daae19b9

Source dataset

uspto-grants-1995_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05438054