Structure‐Guided Engineering of Alcohol Dehydrogenase for the Stereodivergent Synthesis of Amino Alcohols via Desymmetrization of Cyclic Diketones

Chiral cyclic vicinal amino alcohols constitute essential structural motifs in numerous pharmaceutical agents, yet their asymmetric synthesis from readily available symmetric precursors remains a formidable challenge due to difficulties in controlling stereochemistry and preventing over-reduction. Herein, we report a stereodivergent, one-pot dual-enzyme cascade that successfully overcomes these limitations to access all four stereoisomers of 2-aminocyclohexanol from 1,2-cyclohexanedione. Central to this strategy is the development of a "rudder" model-guided protein engineering approach, which reshaped the active site of Lactobacillus kefiri alcohol dehydrogenase (LkADH). This rational design yielded two key mutants, A145Q/G195L and I144Y/G195N, which exhibit exquisite stereocomplementary control over the critical monoreduction step. When coupled with stereoselective amine transaminases, this cascade operates with exceptional efficiency, delivering the target amino alcohols with yields up to 99% and excellent optical purity (> 99% ee and up to 99% de). This methodology not only provides a robust platform for the high-atom-economy synthesis of high-value chiral building blocks but also demonstrates the power of structure-based enzyme redesign in solving complex synthetic problems.