Asymmetric Synthesis of (2S,3R)- and (2S,3S)-2-Aminomethyl-3-hydroxy-3-phenylpropanoic Acids via a Chiral NiII Complex of a Schiff Base Prepared from β-Alanine and (S)-2-[-N-(-N'-benzyl)prolylamino]benzophenone

A chiral Ni^II complex of a Schiff base derived from β-alanine and (S)-2-N-(N'-benzylprolyl)aminobenzophenone (BBP) undergoes an NaH-promoted reaction with benzaldehyde a mixture of two diastereoisomeric complexes which, after chromatographic separation on SiO₂ and decomposition with acid, give optically pure (2S,3R)- and (2S,3S)-2-aminomethyl-3-hydroxy-3-phenylpropanoic acids.