Stereoselective Bioreduction of Telluro‐Acetophenones to Optically Active Hydroxy Tellurides

Organotellurium compounds exhibit a broad range of useful applications in organic synthesis, materials science and medicinal chemistry fields. Despite their increasing applicability, the synthesis of enantiomerically pure organotellurium compounds remains nowadays scarcely reported in the literature. Herein, the chemical synthesis and biocatalyzed reductions of a set of telluro‐acetophenones using both (R) and (S)‐selective alcohol dehydrogenases (ADHs) is described for the first time, obtaining enantiomerically enriched hydroxy tellurides with excellent selectivities under very mild reaction conditions. On the one hand, enantiopure para‐substituted (S)‐hydroxy tellurides were obtained using the Ras‐ADH (77–95 % conversion) and ADH‐A (52–75 %), the ADH‐A leading to the enantiopure (S)‐hydroxy tellurides substituted at the meta‐position (69–75 %). On the other hand, the evo‐1.1.200 displayed high selectivity towards the preparation of optically alcohols with substitutions at the para‐position of the aromatic ring (60–68 % conversion and 92–97 % ee), while the Lb‐ADH led to the best results when reducing bulky ketones at the meta‐position (79–82% conversion and 88–99 % ee).