Highly stereospecific epimerization of alpha-amino acids: conducted tour mechanism

J Org Chem. 2003 Aug 22;68(17):6571-5. doi: 10.1021/jo034130c.


The highly stereospecific and regiospecific recognition of alpha-amino acids exhibited by a novel Co(III) metal complex embodied in the experimental work (Nature 1999, 401, 254) is rationalized from the energetics and structural characteristics with the use of density functional calculations. The steric repulsion between the chiral center of the receptor [Co(III) complex] and alanine has been a cause for the discrimination of complex stabilities. The energies evaluated for all possible alanine binding modes clearly reveal regiospecificity. Our main emphasis is laid on the base-catalyzed epimerization reaction that drives the stereospecific recognition to near completion. The conducted tour mechanism is found to be the most likely candidate. A similar role by the equivalent Zn(II) complex is found.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Stereoisomerism
  • Thermodynamics
  • X-Ray Diffraction


  • Amino Acids