Bakers' Yeast Reduction of γ and δ Ketonitriles: Intermediates for the Synthesis of (S)-5-Hexanolide and Other Chiral Lactones

A number of γ and δ ketonitriles have been synthesized and their reduction with bakers yeast carefully studied. Both 4-oxopentanenitrile and 5-oxohexanenitrile are reduced in moderate yields to the corresponding (S) alcohols of high ee while other substrates gave products of varying optical purities. These alcohols are useful intermediates for the preparation of chiral lactones, including the synthetically important (S)(−)-4-methylbutyrolactone and (S)-(−)-5-hexanolide.