ChEBI: The (S)-enantiomer of 2-hydroxy-4-methylpentanoic acid. Derived from the metabolism of the branched-chain amino acids, it belongs to the 2-hydroxycarboxylic acid group of amino acid metabolites.
GENERAL STEPS: L-leucine (24.92 g, 0.189 mol) was dissolved in 1.25 M H2SO4 (125 mL), stirred and cooled to 0°C. An aqueous solution of sodium nitrite (19.73 g, 0.286 mol) (100 mL) was added dropwise with stirring. After addition, the reaction mixture was continued to be stirred at 0°C for 2 hours, and then brought to room temperature and stirred for 15 hours. After completion of the reaction, the reaction mixture was extracted with ether (6 x 75 mL). The organic layers were combined, dried with anhydrous MgSO4, filtered and concentrated under reduced pressure to remove the ether to give the crude product L-α-hydroxyisocaproic acid (2c or 2d). The crude product was purified by solvent recrystallization from hexane-ether mixture.
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