From a Sequential to a Concurrent Reaction in Aqueous Medium: Ruthenium‐Catalyzed Allylic Alcohol Isomerization and Asymmetric Bioreduction

The ruthenium-catalyzed redox isomerization of allylic alcohols was successfully coupled with the enantio-selective enzymatic ketone reduction (mediated by KREDs) in a concurrent process in aqueous medium. The overall transformation, formally the asymmetric reduction of allylic alcohols, took place with excellent conversions and enantio-selectivities, under mild reaction conditions, employing commercially and readily available catalytic systems, and without external coenzymes or cofactors. Optimization resulted in a multistep approach and a genuine cascade reaction where the metal catalyst and biocatalyst coexist from the beginning.