Preparation of optically pure α-methyl-α-amino acids via alkylation of the nickel(II) Schiff base of (R,S)-alanine with (S)-2-N-(N′-benzylprolyl)aminobenzaldehyde

Abstract

Chiral nickel(II) complexes of Ala with (S)-2-N-(N′-benzylprolyl)aminobenzaldehyde [(S)-bba] were alkylated with alkyl halides and the diastereoisomeric complexes formed were separated on SiO₂; their decomposition led to the isolation of enantiomerically pure (R)- and (S)-α-alkyl-α-amino acids with recovery of the initial (S)-bba.