Amination of a Green Solvent via Immobilized Biocatalysis for the Synthesis of Nemtabrutinib

“Enzymes are capable of unique and selective transformations that can enable efficient chemical production. While many industrial processes have been developed using free enzymes in aqueous solutions, immobilizing enzymes on a solid support can offer considerable advantages, including improved reaction efficiency, enzyme stability, the ability to perform reactions in non-aqueous media, and simplified separation of the product from the enzyme. Herein, we describe the development of a biocatalytic transaminase reaction of Cyrene (2) utilizing an immobilized, evolved transaminase enzyme in an organic solvent to provide amine intermediate 3a en route to Bruton’s tyrosine kinase (BTK) inhibitor nemtabrutinib. Enzyme immobilization is critical to facile isolation of the water-soluble product. Improved reaction kinetics and diastereoselectivity were achieved by bridging directed enzyme evolution with the selection of an optimal reaction solvent and solid support for immobilization, enabling a unified solvent system and direct isolation of 3a as a crystalline salt with dr > 50:1.”

Highlights:

• “We also hypothesized that immobilization of the transaminase enzyme could further improve the enzyme’s stability therefore enabling extended operation in organic solvents.”
• “The reactions were tested using a SpinChem rotating bed reactor, which holds the catalyst in a rotating basket suspended in the bulk liquid, allowing automated sampling from the liquid phase.”
• “Through a combination of protein engineering, enzyme immobilization, and reaction optimization, we achieved a streamlined, robust process […] and enables simplified, direct isolation of 3a (product) as a crystalline salt with dr > 50:1.”