Hydroxynitrile Lyase-Catalyzed Synthesis of Enantiopure Cyanohydrins in Biocatalytic Active Static Emulsions (BASE) with Suppression of the Non-Enzymatic Side Reaction

The use of biocatalytic active static emulsions (BASE) was investigated for the hydroxynitrile lyase‐catalyzed synthesis of enantiopure cyanohydrins. With this technique a full suppression of the undesired racemic non‐enzymatic side reaction was facilitated, even at unusually high pH within the aqueous phase. Thus the full catalytic potential at the optimum pH was achieved with the hydroxynitrile lyase from Manihot esculenta. As proof of principle, a series of carbonyl compounds was successfully converted to the corresponding cyanohydrins with high yields and enantioselectivities, including several benzaldehyde derivatives and aliphatic ketones. Furthermore, several mandelic acid derivatives were obtained on a multi‐gram scale after hydrolysis, which proves the synthetic applicability of BASE‐immobilized hydroxynitrile lyases.