A robust two-enzyme system composed of an immobilized ketoreductase (KRED1-Pglu) and a glucose dehydrogenase (BmGDH) was developed via immobilization on aldehyde agarose for the stereoselective reduction of different ketones. The immobilized ketoreductase/glucose dehydrogenase system was continuously used in a flow reactor for weeks, even in the presence of concentrations of DMSO up to 20%.

A new mild and efficient process for the aqueous preparation of aldehydes, which are employed as flavour and fragrance components in food, beverage, cosmetics, as well as in pharmaceuticals, was developed using a continuous‐flow approach based on an immobilised pure transaminase‐packed bed reactor. HEWT, an ω‐transaminase from the haloadapted bacterium Halomonas elongata, has been selected for its excellent stability and substrate scope. Sixteen different amines were rapidly (3–15 min) oxidised to the corresponding aldehydes (90 to 99 %) with only 1 to 5 equivalents of sodium pyruvate. The process was fully automated, allowing for the in‐line recovery of the pure aldehydes (chemical purity >99 % and isolated yields above 80 %), without any further work‐up procedure.

The chemoenzymatic flow synthesis of enantiomerically pure captopril, a widely used antihypertensive drug, is accomplished starting from simple, inexpensive, and readily available reagents. The first step is a heterogeneous biocatalyzed regio‐ and stereoselective oxidation of cheap prochiral 2‐methyl‐1,3‐propandiol, performed in flow using immobilized whole cells of Acetobacter aceti MIM 2000/28, thus avoiding the use of aggressive and environmentally harmful chemical oxidants. The isolation of the highly hydrophilic intermediate (R)‐3‐hydroxy‐2‐methylpropanoic acid is achieved in‐line by using a catch‐and‐release strategy. Then, three sequential high‐throughput chemical steps lead to the isolation of captopril in only 75 min. In‐line quenching and liquid–liquid separation enable breaks in the workflow and other manipulations to be avoided.

Enantiomerically enriched 2-hydroxymethylalkanoic acids were prepared by oxidative desymmetrisation of achiral 1,3-diols using immobilized cells of Acetobacter aceti in water at 28 °C. The biotransformations were first performed in batch mode with cells immobilized in dry alginate, furnishing the desired products with high molar conversion and reaction times ranging from 2 to 6 h. The biocatalytic process was intensified using a multiphasic flow reactor, where a segmented gas–liquid flow regime was applied for achieving an efficient O2-liquid transfer; the continuous flow systems allowed for high yields and high biocatalyst productivity.

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