Chemical approach for interconversion of (S)- and (R)-α-amino acids

Here we report a general method for the preparation of unnatural (R)-alpha-amino acids via complexation of alpha-(phenyl)ethylamine derived chiral reagent (S)-3 with various (5)-alpha-amino acids. The reactions proceed with synthetically useful chemical yields and thermodynamically controlled diastereoselectivity. Chiral reagent (S)-3 can be conveniently recovered and reused without any loss of enantiomeric purity and reactivity.