A chemo-enzymatic route to synthesize (S)-γ-valerolactone from levulinic acid

Journal
Applied microbiology and biotechnology  
Volume
97
Issue
9
Start Page
3865
End Page
3873
Citation
Applied Microbiology and Biotechnology 9 (97): 3865-3873 (2013)
Publisher DOI
10.1007/s00253-012-4652-5
Scopus ID
2-s2.0-84885897786
PubMed ID
23296499
Publisher
Springer
Levulinic acid is a feasible platform chemical derived from acid-catalyzed hydrolysis of lignocellulose. The conversion of this substrate to (S)-γ- valerolactone ((S)-GVL) was investigated in a chemo-enzymatic reaction sequence that benefits from mild reaction conditions and excellent enantiomeric excess of the desired (S)-GVL. For that purpose, levulinic acid was chemically esterified over the ion exchange resin Amberlyst 15 to yield ethyl levulinate (LaOEt). The keto ester was successfully reduced by (S)-specific carbonyl reductase from Candida parapsilosis (CPCR2) in a substrate-coupled cofactor regeneration system utilizing isopropanol as cosubstrate. In classical batch experiments, a maximum conversion of 95% was achieved using a 20-fold excess of isopropanol. Continuous reduction of LaOEt was carried out for 24 h, and a productivity of more than 5 mg (S)-ethyl-4-hydroxypentanoate (4HPOEt) per μg CPCR2 was achieved. Afterwards (S )-4HPOEt (>99%ee) was substituted to lipase-catalyzed lactonization using immobilized lipase B from Candida antarctica to yield (S)-GVL in 90% overall yield and >99% ee.
Subjects
Asymmetric reduction
Chemo-enzymatic reaction sequence
CPCR2
Enantioselective
Technical levulinic acid
DDC Class
570: Biowissenschaften, Biologie