Enzymatic production of (S)-3-cyano-5-methylhexanoic acid ethyl ester with high substrate loading by immobilized Pseudomonas cepacia lipase

(S)-3-Cyano-5-methylhexanoic acid ethyl ester is a valuable synthetic intermediate for pregabalin. Immobilized lipase PS from Pseudomonas cepacia was screened and shown to be the best biocatalyst for the enantioselective hydrolysis of 3-cyano-5-methylhexanoic acid ethyl ester, a racemic mixture involving a β-stereocenter. The optimum temperature and pH for the biocatalytic process were 35 °C and 6.0, respectively. Lipase PS IM exhibited a strong tolerance toward high substrate concentrations of up to 2.0 M (366 g/l). In the scaled-up biotransformation, (S)-3-cyano-5-methylhexanoic acid ethyl ester was produced in 0.89 M (162.9 g/l), 99.2% ee, and 44.5% yield. These results indicated that lipase PS IM catalyzed the preparation of (S)-3-cyano-5-methylhexanoic acid ethyl ester and could be used as an efficient route for the large-scale production of pregabalin.

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(S)-3-Cyano-5-methylhexanoic acid ethyl esterC10H17NO2[α]D20=-12.2 (c 1.1, CH3OH)Absolute configuration: (S)Source of chirality: Kinetic resolution

Potassium (S)-3-Cyano-5-methylhexanoateC8H12NO2K[α]D20=-22.5 (c 1.1, CH3OH)Absolute configuration: (S)Source of chirality: Kinetic resolution