Oxazoline-4-acetate derivative 3 that could be readily obtained from L-aspartic acid was subjected to highly stereoselective hydroxylation, and subsequent Mitsunobu inversion of the hydroxyl group led to (2S,3R)-3-amino-3-benzyl-2-hydroxybutanoic acid derivative 8 in a good yield. Coupling of 8 with L-leucine benzyl ester and subsequent cleavage of the protective groups provided (−)-bestatin 1 in a high yield.
