Deracemization through Concurrent Oxidation and Reduction

Significance

Biocatalytic deracemization of sec-alcohols rac-1 has been achieved through a concurrent stereoselective oxidation-reduction sequence affording the S-enantiomer S-1 in highly enantioenriched form (up to er > 99.5:0.5). The authors have identified resting cells of Alcaligenes faecalis DSM 13975 as a highly active and R-enantioselective catalyst for the oxidation of sec-alcohols. Molecular oxygen serves as oxidant. In the reduction step, an S-selective alcohol dehydrogenase, either ADH-‘A’ or RE-ADH, in combination with a cofactor recycling system (glucose/ GDH) was effective. The method has also been applied to the stereoinversion of an enantiopure sec-alcohol. A related system gives access to the R-enantiomer through S-enantioselective oxidation and R-stereoselective reduction.