Hydrochloric Acid → (2S)-2-Hydroxy-2,3-dimethylbutanoic acid

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Reaction Steps

To a magnetically stirred solution of (7) (94 g, 0.47 mol) in methanol (450 mL) and water (100 mL), in a 1-L, one-neck, round-bottom flask was added potassium hydroxide pellets (48 g, 0.85 mol, 1.8 equivalents). The reaction was then heated to reflux for 30 minutes. The mixture was cooled to room temperature and concentrated in vacuo to afford a milky suspension. This mixture was diluted with water (100 mL), cooled to 0° C., and acidified with concentrated hydrochloric acid (15 mL) to pH 6. Additional water (100 mL) was added, and the mixture extracted with ethyl acetate (3×400 mL). The combined organics were washed with water (1×600 mL), saturated aqueous chloride solution (1×600 mL), dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated in vacuo to afford a pale yellow oil which on drying in vacuo afforded 59 g (94% yield) of (8) as a crystalline solid. The 1H NMR of the product was consistent with the material previously prepared.

Provenance & Evidence