Chemo‐ and Stereoselective Reduction of β‐Keto‐α‐oximino Nitriles by Using Baker's Yeast

The baker’s yeast mediated reduction of β-keto-α-oximino nitriles 3 at 20 °C gave β-hydroxy-α-oximino nitriles 4 in high yields with high enantiomeric purity [enantiomeric excess (ee) values 99%]. At room temperature, the same reaction afforded the product in a slightly lower yield. The β-hydroxyα-oximino nitriles 4 were obtained as single stereoisomers according to chiral GC–MS analyses and the 1 H and 19 F NMR spectra of the corresponding Mosher esters. The abso