Water → Pregabalin

Participants

Reaction Conditions

Reaction Steps

A mixture of potassium (S)-3-cyano-5-methylhexanoate (20 g, 103.5 mmol), water (50 mL), 45% KOH (12 g), isopropanol (12 g), and Raney Nickel were shaken overnight in a Parr Shaker under 50 psi of hydrogen. The mixture was filtered, heated to approximately 50° C., treated with acetic acid (6.5 mL) and stirred overnight at room temperature. The mixture was then adjusted to slightly above pH 7 with 45% KOH and concentrated under vacuum to remove most of the isopropanol. Isopropanol (20 mL) was added to the mixture, which was then acidified with acetic acid, stirred overnight at room temperature, and filtered to give 4.3 g of (S)-3-aminomethyl-5-methylhexanoic acid as a white crystalline solid. The enantiomeric purity was determined to be 100% e.e. by preparing a derivative of (S)-3-aminomethyl-5-methylhexanoic acid using Marfey's reagent (Na-(2,4-dinitro-5-fluorophenyl)-L-alaninamide) and analyzing by HPLC on a BDS Hypersil C18 column (250×4.6 mm, 5μ) eluted with acetonitrile:1% triethylamine (pH 3) (38:62, v/v).

Provenance & Evidence