Synthesis of α-hydroxy-β-amino acids from chiral cyanohydrins

(−)-(R,E)-2-hydroxy-3-pentenenitrile 1, obtained by R-oxynitrilase catalyzed addition of HCN to 2-butenal, was shown to be an excellent chiral starting material for the synthesis of α-hydroxy-β-amino acids of high enantiomeric and diastereomeric purity. The synthesis of N-benzyl (S)-isoserine 7a and (2S,3S)-isoallothreonine 7b, as well as N-benzoyl (2S,3S)-3-phenylisoserine 14 is reported.