Hydrochloric Acid → (2R,3S)-3-((tert-Butoxycarbonyl)amino)-2-hydroxy-4-phenylbutanoic acid

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Reaction Conditions

Reaction Steps

To (4S,5R)-4-benzyl-2-oxo-5-oxazolidinecarboxylic acid obtained in the same manner as in Example 4 (2.39 g) were added 2-propanol (6.7 ml) and 8N aqueous potassium hydroxide solution (6.7 ml), and the mixture was stirred at 90° C. for 3 hr. The mixture was cooled to room temperature and adjusted to pH=8 with 6N aqueous hydrochloric acid solution. To the reaction mixture was added di-tert-butoxycarbonate (2.83 g) dissolved in 2-propanol (6.7 ml) and the mixture was stirred at room temperature for 12 hr. After adjusting the mixture to pH=3, dichloromethane (20 ml) was added to extract the mixture. The solvent of the organic layer was removed under reduced pressure to give crude crystals of (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-4-phenylbutyric acid (2.88 g). The crude crystals were analyzed by HPLC to confirm that (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-4-phenylbutyric acid (2.55 g, yield 80%) was obtained.

Provenance & Evidence