Microbiological enantioselective reduction of ethyl acetoacetate

Different microorganisms (MOs) were used to carry out the enantioselective reduction of ethyl acetoacetate to (S)-(+)-3-hydroxybutanoate or (R)-(−)-3-hydroxybutanoate. Surprisingly, the commercially available Saccaromyces cerevisiae led to only 58% ee of (S)-(+)-3-hydroxybutanoate. Other MOs such as Hansenula sp. and Dekera sp. furnished the same enantiomer with greater ees, 81 and 73%, respectively. Aspergilus niger and Kluyveromyces marxianus although leading to lower ees, 30 and 18%, yielded the opposite enantiomer. All reactions proceeded to greater than 85% conversion. This is the first report on the use of Hansenula sp. and Dekera sp. in reductions of β-ketoesters.