(S)-(-)-2-Hydroxy-3,3-dimethylbutyric acid

20859-02-3

21641-92-9

General procedure for the synthesis of (S)-2-hydroxy-3,3-dimethylbutanoic acid from L-tert-leucine: 3,3-dimethylbutanoic acid (1 g, 7.5 mmol) was dissolved in an aqueous solution of 1 M sulfuric acid (15 ml) and cooled to 0°C. An aqueous solution (8 ml) of sodium nitrite (1.0 g, 15 mmol) was slowly added while keeping the reaction temperature below 5°C. The reaction mixture was stirred at the same temperature overnight. After completion of the reaction, it was treated with a saturated solution of ammonium sulfate followed by extraction with ether (5 x 25 ml). The organic phases were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford (S)-2-hydroxy-3,3-dimethylbutyric acid (0.27 g, 67% yield) as a colorless oil, which crystallized after standing. The product was confirmed by 1H NMR (400 MHz, CD3OD): δ 3.41 (s, 1H), 1.25 (s, 9H). LCMS analysis showed m/z 133.2 [M + H]+ with a retention time Tr = 0.39 min (using a Gemini 5u C18 150 × 4.60 mm 5 µm column at a flow rate of 3.5 ml/min with gradient elution). conditions: 5-100% acetonitrile/water with 0.1% acetic acid modifier).