Discovery and Process Development of a Scalable Biocatalytic Kinetic Resolution toward Synthesis of a Sterically Hindered Chiral Ketone

Sterically hindered chiral ketones are useful intermediates in the synthesis of active pharmaceutical ingredients. Here, we report a scalable and highly enantioselective synthesis through a kinetic resolution process promoted by a wild-type ketoreductase (KRED) enzyme. The process was investigated thoroughly, including DoE optimizations and a kinetic study. Scale-up demonstrations on up to 0.8 kg revealed an enzyme aggregation/deactivation challenge, and solutions were provided to obtain the desired enantiomer in high yields and enantiomeric excesses with relatively low enzyme loadings (2–4 wt %).