A simple method for determining the absolute configuration of α-amino acids

Chiral α-amino acids react with 2-methoxy - 2,4 - diphenyl - 3 (2 H ) - furanone 1 to afford N -substituted 3,5 - diphenyl - 5 - hydroxy - 2 - pyrrolin - 4 - ones 2 . The characteristic cotton effects given by these chromophoric derivatives provide a means for the determination of the absolute configuration of the parent amino acids. The longest wavelength(first) extremum in the chiroptical spectra (ORD and CD) of the l -amino acid derivatives is always positive, while it is negative for the d -amino acid derivatives.