Immobilized Whole-Cell Transaminase Biocatalysts for Continuous-Flow Kinetic Resolution of Amines

Immobilization of transaminases creates promising biocatalysts for production of chiral amines in batch or continuous-flow mode reactions. E. coli cells containing overexpressed transaminases of various selectivities and hollow silica microspheres as supporting agent were immobilized by an improved sol-gel process to produce immobilized transaminase biocatalysts with suitable stability and mechanical properties for continuous-flow applications. The immobilized cell-based transaminase biocatalyst proved to be durable and easy-to-use in kinetic resolution of four racemic amines 1a-d. The batch and continuous-flow mode kinetic resolutions with transaminase biocatalyst of opposite stereopreference provided access to both enantiomers of the corresponding amines. By using the most suitable immobilized transaminase biocatalysts, this study describes the first transaminase-based approach for the production of both pure enantiomers of 1-(3,4-dimethoxyphenyl)ethan-1-amine 1d.