Poly-ε-caprolactone (PCL) is chemically produced on an industrial scale in spite of the need for hazardous peracetic acid as an oxidation reagent. Although Baeyer-Villiger monooxygenases (BVMO) in principle enable the enzymatic synthesis of ε-caprolactone (ε-CL) directly from cyclohexanone with molecular oxygen, current systems suffer from low productivity and are subject to substrate and product inhibition. The major limitations for such a biocatalytic route to produce this bulk chemical were overcome by combining an alcohol dehydrogenase with a BVMO to enable the efficient oxidation of cyclohexanol to ε-CL. Key to success was a subsequent direct ring-opening oligomerization of in situ formed ε-CL in the aqueous phase by using lipase A from Candida antarctica, thus efficiently solving the product inhibition problem and leading to the formation of oligo-ε-CL at more than 20 g L(-1) when starting from 200 mM cyclohexanol. This oligomer is easily chemically polymerized to PCL.

No abstract

All nor(pseudo)ephedrine isomers can be synthesized step-efficiently in two different 1-pot 2-step biocatalytic cascade reactions in high optical purities.

No abstract

The synthesis of enantiopure amines via amine transaminases involves several challenges including unfavorable reaction equilibria and product inhibition. Described here is a non‐catalytic approach to overcome such problems by using an in situ‐product crystallization (ISPC) to selectively remove a targeted product amine from an amine transaminase‐catalyzed reaction. The continuous removal of the product amine from its reaction solution as a barely soluble salt effectively yields a displacement of the reaction equilibrium towards the products and facilitates a simple downstream processing approach via filtration. The targeted product amine is eventually obtained from the salt, while the counterion compound can be easily recycled.

By the combination of biocatalyst design and reaction engineering, the so far not stereoselectively accessible (S)-phenylacetylcarbinol could be enzymatically synthesized with product concentrations >48 g L−1 and an enantiomeric excess up to 97%.

No abstract

No abstract