One Pot Asymmetric Synthesis of (R)‐Phenylglycinol from Racemic Styrene Oxide via Cascade Biocatalysis

(R)-Phenylglycinol is an important chiral building block for pharmaceutical and fine chemical industry, and its efficient synthesis from cheap and commercially available starting materials is challenging and highly desirable. Herein, a new three-step one-pot cascade system employing epoxide hydrolase, glycerol dehydrogenase, and omega-transaminase was designed for the asymmetric synthesis of (R)-phenylglycinol from racemic styrene oxide. A cofactor self-sufficient system employing AlaDH/L-Ala was utilized for the regeneration of expensive cofactor NAD(+) and removal of by-product pyruvate. Furthermore, in situ product removal by cation resin adsorption was used to drive the thermodynamic equilibrium of the cascade reaction to the direction of product generation. Finally, optically pure (R)-phenylglycinol was successfully produced from racemic styrene oxide with high yield (81.9 %) and excellent enantioselectivity (99 % ee).