Tailored Particle Catalysts for Multistep One‐pot Chemoenzymatic Cascade in Pickering Emulsions

Abstract

Chemoenzymatic cascades are an important tool for advanced synthesis in chemistry. However, these cascades are often limited due to the incompatibility issue between two distinct catalysts and reactions. To address this issue, we present a simple multistep one-pot platform, in which nanoparticle catalysts are prepared to allow chemo-and biocatalytic reactions performed sequentially in water and Pickering emulsions. The preparation of particle catalysts is accomplished in just two steps by polymer modifications and [RuCl 2 (pcymene)] 2 coordination, while the benefits of using them for chemoenzymatic synthesis are multifaceted. They act not only as asymmetric catalysts for asymmetric transfer hydrogenation from acetophenone to 1-phenylethanol in water with up to 99 % conversion and 93 % ee, but also as an emulsifier to form stable Pickering emulsions. By the addition of Candida antarctica lipase B into the emulsions, the second-step reaction of enantioselective acylation was achieved with 38 % conversion and 99 % ee. Therefore, we successfully present a simple method to enable chemoenzymatic cascades by combining particle catalysts and enzymes in water and Pickering emulsions in a sequential fashion, which can be generalized for other cascade syntheses with different chemo-and biocatalysts in the future.

One-pot chemo- and photo-enzymatic linear cascade processes

“…The use of particle-assisted emulsions, also referred to as Pickering emulsions, is an alternative to the use of molecular surfactants to confine the catalytic species. Recently, Wu et al 387 reported the Pickering chemo-enzymatic cascade for the one-pot synthesis of chiral esters from ketones (Scheme 103). The authors prepared a silica nanoparticle catalyst containing anchored chiral Ru( ii ) complexes that act not only as heterogeneous metal catalysts to reduce the ketone into the alcohol, but also as active emulsifiers that form Pickering emulsions to encapsulate the lipase CALB, which catalyzes the subsequent enantioselective esterification of the alcohol.…”