Pickering Emulsion Promoted Interfacial Sequential Chemo-Biocatalytic Reaction for the Synthesis of Chiral Alcohols from Styrene.

Abstract

Chemo-biocatalytic cascades have emerged as a promising approach in the realm of advanced synthesis. However, reconciling the incompatible reaction conditions among distinct catalytic species presents a significant challenge. Herein, we introduce an innovative solution using an emulsion system stabilized by Janus silica nanoparticles, which serve as a bridge for both chemo-catalysts and biocatalysts at the interface. The chemo-catalyst is securely anchored within a hydrophobic polymer matrix, ensuring its residence in an organic environment. Meanwhile, the negatively charged E. coli cells containing enzymes are attracted to the aqueous phase at the interface, facilitating their optimal positioning. We demonstrate the efficacy of this system through a two-step cascade reaction. Initially, the oxidation of styrene to acetophenone using palladium as a chemocatalyst achieves a 6-fold increase in yield compared to the control system. Subsequently, the reduction of achiral acetophenone to its chiral alcohol derivative presents a 17-fold yield enhancement relative to that of the control reaction. Importantly, our system exhibits versatility, accommodating a wide range of substrates for both individual and sequential reactions. This work not only validates the concept but also paves the way for the integration of chemo- and biocatalysts in the synthesis of a broader array of high-value chemical compounds.