Chemoenzymatic Dynamic Kinetic Resolution of a Tertiary Alcohol Based on Compartmentalization of Oxovanadium and Lipase Catalysts by Means of a Polydimethylsiloxane Thimble

Abstract

Addressing the challenging field of chemoenzymatic dynamic kinetic resolution (DKR) of tertiary alcohols, for which so far only one example exists in the literature, we combined biocatalytic esterification and oxovanadium-catalyzed racemization, operating both steps in two different compartments of one reactor. The compartmentalization of the two heterogeneous catalysts, namely, immobilized lipase A from Candida antarctica (CAL-A) or its mutant and oxovanadium species on mesoporous silica, was achieved using a polydimethylsiloxane thimble, avoiding contact of the oxovanadium with water, thus maintaining the catalyst’s activity and thereby successfully improving the efficiency of the DKR. Utilizing the immobilized double mutant CAL-A V278S + S429G, the ester was obtained in 62% yield with excellent enantiomeric excess of >99% ee.