A one-pot consecutive two-enzyme sequential cascade toward chiral γ-butyrolactones using an enoate reductase as well as alcohol dehydrogenases in combination with a glucose dehydrogenase is reported. In this scalable process, the products were obtained in high yield (up to 90%) and with perfect enantioselectivity (98→99% ee). The starting materials, ethyl 4-oxo-pent-2enoates, are readily accessible via Wittig-type reactions. Furthermore, the stereoselectivity of the enoate reductase catalyzed reaction has been studied in detail, leading to deeper insights into the mechanism of this enzyme.

Ene reductases from the Old Yellow Enzyme family are versatile biocatalysts useful for the synthesiso fo ptically active compounds. Oned isadvantage of biocatalysts when compared to competing catalysts in chemical syntheses is that often only one stereoisomer of the product is available.A nother drawback can be the lack of activity in certain enzyme-substrate combinations.W ew ere able to approach botho ft hese challenges rationally in the case of the enzymatic synthesis of methyl3 -hydroxy-2-methylpropanoate (commonly denoted as the Roche ester)a nd derivatives thereof using the ene reductase YqjM.B yahighly efficient, concept-based approach of designingmutant variants of YqjM and engineering substrates we could alter boththe rate constant and the enantioselectivity of the reaction. Preparative scale reactions have been performed with successful mutants. In addition,t he iterative modification of the substrate gavee xperiment-basedi nsights into the binding mode of the Roche ester precursor andits derivatives.

Enantiomerically pure (R)-profen derivatives and intermediates are synthesised utilising the enzyme YqjM, an ene reductase from Bacillus subtilis. After optimisation of the reaction conditions, the chemoenzymatic approach was applied for the first time in the synthesis of (R)-flurbiprofen methyl ester.