An expeditious synthesis of (2R,3S)-3-amino-4-cyclohexyl-2-hydroxybutyric acid (2) and (2S,3R)-3-amino-2-hydroxy-4-phenylbutyric acid (4), the key components of the renin inhibitor (1) and bestatin (3), respectively, have been accomplished by featuring highly diastereoselective formation of cyanohydrin acetates from α-alkoxycarbonylamino aldehydes under phase-transfer conditions.