Cyanide-Free and Broadly Applicable Enantioselective Synthetic Platform for Chiral Nitriles through a Biocatalytic Approach

A cyanide-free platform technology for the synthesis of chiral nitriles by biocatalytic enantioselective dehydration of a wide range of aldoximes is reported. The nitriles were obtained with high enantiomeric excess of >90% ee (and up to 99% ee) in many cases, and a privileged substrate structure with respect to high enantioselectivity was identified. Furthermore, a surprising phenomenon was observed for the enantiospecificity that is usually not observed in enzyme catalysis. Depending on whether the E or Zisomer of the racemic aldoxime substrate was employed, one or the other enantiomer of the corresponding nitrile was formed preferentially with the same enzyme.