Stereospecific Synthesis of d-Isothreonine from l-Threonine

Abstract
D-Isothreonine, (2R,3S)-3-amino-2-hydroxybutanoic acid (4), was readily prepared by the ammonolysis of optically active 2-bromo-3-hydroxybutanoic acid derived from l-threonine. The configuration of 4 was deduced from the shift of molecular rotation, Cotton effect in ORD curve of 4, and NMR measurement of its oxazolidone derivative.