Deracemization and Stereoinversion of Alcohols Using Two Mutants of Secondary Alcohol Dehydrogenase from Thermoanaerobacter pseudoethanolicus

Abstract

We developed a one‐pot sequential two‐step deracemization approach to chiral alcohols using two mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). This approach relies on consecutive non‐stereospecific oxidation of alcohols and stereoselective reduction of their prochiral ketones using two mutants of TeSADH with poor and good stereoselectivities, respectively. More specifically, W110G TeSADH enables a non‐stereospecific oxidation of alcohol racemates to their corresponding prochiral ketones, followed by W110V TeSADH‐catalyzed stereoselective reduction of the resultant ketone intermediates to enantiopure (S)‐configured alcohols in up to > 99 % enantiomeric excess. A heat treatment after the oxidation step was required to avoid the interference of the marginally stereoselective W110G TeSADH in the reduction step; this heat treatment was eliminated by using sol‐gel encapsulated W110G TeSADH in the oxidation step. Moreover, this bi‐enzymatic approach was implemented in the stereoinversion of (R)‐configured alcohols, and (S)‐configured alcohols with up to > 99 % enantiomeric excess were obtained by this Mitsunobu‐like stereoinversion reaction.