Biosynthesis of α-substituted β-ketoesters via the tandem Knoevenagel
condensation-reduction reaction using a single enzyme
Abstract
Saturated α-substituted β ketoesters are important building blocks in
synthesis of pharmaceuticals and agrochemicals. Herein, we report a
one-pot biosynthesis of α-substituted β ketoesters via Knoevenagel
condensation and reduction of received unsaturated alkenes in situ,
catalyzed by single ene-reductase (NerA). A series of inexpensive and
readily available aldehydes and 1,3-diketones were condensed and reduced
by NerA in aqueous solution at room temperature. We also note that low
loadings (3 mg/ml) of NerA are sufficient to facilitate the cascade
process, both E and Z isomeric intermediates can be reduced effectively
and improved the overall yield up to 95%. Meanwhile, the method can be
applied in preparative-scale synthesis of pharmaceutical intermediate.
This process conforms to the concepts of green chemistry and shows
advantages for synthesis of high value saturated α-substituted β
ketoesters.