Rapid determination of enantiomeric excess of protected amino acids by catalytic amounts of chiral reagent

A protocol for the determination of enantiomeric excess (ee) of protected chiral amino acids using the frequency shifts in nuclear magnetic resonance (NMR) spectra induced by catalytic amounts of chiral auxiliary is described. Principal component analysis (PCA) method shows the difference in NMR shifting which shows no obvious pattern, Least Square-Support Vector Machine (LS-SVM) technique with high nonlinear processing ability is employed to analyze unknown ee values.