Hydrochloric Acid → (R)-2-((tert-Butoxycarbonyl)amino)-4,4-dimethylpentanoic acid

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Reaction Steps

N-tert-Butoxycarbonyl-3-tert-butyl-D-alanine methyl ester (Example 5A, 60 g, 231 mmol) is dissolved in tetrahydrofuran p.a. (463 ml). At RT, a solution of lithium hydroxide monohydrate (19.4 g, 462.7 mmol) in water (463 ml) is slowly added dropwise. When the HPLC chromatogram (Method 2) shows complete conversion (about 20 h), the reaction mixture is cautiously adjusted to pH 3-4 with 1 N aqueous hydrochloric acid with ice cooling. Sodium chloride (150 g) is added to the reaction mixture in order subsequently to extract it with ethyl acetate (2×500 ml). The combined organic phases are dried with a saturated sodium chloride solution and then with sodium sulfate and filtered. The filtrate is concentrated on a rotary evaporator and dried under high vacuum. 55.4 g (98% of theory) of the title compound are obtained.

Provenance & Evidence