Stereochemical Outcome of the Biocatalysed Reduction of Activated Tetrasubstituted Olefins by Old Yellow Enzymes 1–3

The ene‐reductase‐mediated reactions of (E)‐ and (Z)‐stereoisomers of tetrasubstituted activated alkenes were performed by means of isolated old yellow enzymes (OYEs) 1–3. The comprehension of the resulting data required a careful analysis of the stereochemical course of this kind of reaction. The investigation of the bioreduction of tetrasubstituted alkenes allowed us to appreciate the contribution of several factors (configuration of the starting alkene, mechanism of hydrogen addition, substrate binding mode) to the overall stereochemistry of the reaction.