Enzymatic Resolution of Chiral 2-Hydroxy Carboxylic Acids by Enantioselective Oxidation with Molecular Oxygen Catalyzed by the Glycolate Oxidase from Spinach (Spinacia oleracea)

The enzymatic oxidation of a variety of saturated and unsaturated aliphatic derivatives of racemic 2-hydroxy acids 1 to their 2-oxo acids 2 with molecular oxygen catalyzed by the glycolate oxidase from spinach (Spinacia oleracea) was shown to proceed highly enantioselectively. Thus, the glycolate oxidase-catalyzed kinetic resolution provides a convenient biocatalytic method for the preparation of enantiomerically pure (R)-2-hydroxy acids. The absolute configuration of the (R)-2-hydroxy acid 1b was assigned by comparison of the measured optical rotation value with that of the literature data and by application of the exciton-coupled circular dichroism method (ECCD) on its bichromophoric 2-naphthoate 9-methylanthryl derivative 3b. These results establish the ECCD method as a convenient microscale chirooptic tool for the configurational assignment of 2-hydroxy acids.