Stereo‐Controlled Asymmetric Bioreduction of α,β‐Dehydroamino Acid Derivatives

Abstract α,β‐Dehydroamino acid derivatives proved to be a novel substrate class for ene‐reductases from the ‘old yellow enzyme’ (OYE) family. Whereas N‐ acylamino substituents were tolerated in the α‐position, β‐analogues were generally unreactive. For aspartic acid derivatives, the stereochemical outcome of the bioreduction using OYE3 could be controlled by variation of the N ‐acyl protective group to furnish the corresponding ( S )‐ or ( R )‐amino acid derivatives. This switch of stereopreference was explained by a change in the substrate binding, by exchange of the activating ester group, which was proven by 2 H‐labelling experiments.