Synergistic CRISPR–Cas9 Host Engineering and Enzyme Evolution for Enantioselective Synthesis of a Vibegron Pyrrolidine Intermediate

The stereoselective synthesis of chiral pyrrolidine motifs is essential to vibegron production but remains challenging using conventional chemical routes. Here we report an imine reductase (IRED) catalyzed asymmetric imine reduction to access a key vibegron intermediate. Directed evolution afforded a highly efficient variant delivering 94% conversion and >99% d.e. Combined enzyme and host engineering enabled clean whole cell catalysis, establishing a robust and scalable biocatalytic platform.