Enzymatic synthesis of chiral 2-hydroxy carboxylic acids

• Recent advances in biosynthesis of chiral 2-hydroxy carboxylic acids are reviewed.
• Racemase enables dynamic kinetic resolution of chiral 2-hydroxy carboxylic acids.
• Oxynitrilase and nitrilase enable the biosynthesis from aldehydes in one step.
• Bioreduction of α-keto acid esters offers a synthetic approach.
• Bioreduction was successfully performed without addition of external cofactor.

Optically active 2-hydroxy carboxylic acids are widely used not only as key building blocks for the synthesis of various organic compounds, but also as chiral resolving reagents. This review focuses on the recent advances in enzymatic preparation of enantiomerically pure 2-hydroxy carboxylic acids, which mainly includes two approaches: (dynamic) kinetic resolution of racemic 2-hydroxy carboxylic acids and derivatives by hydrolase enzymes, and asymmetric reduction of α-keto acids and esters by carbonyl reductases.