Diastereochemical differentiation of some cyclic and bicyclic beta-amino acids, via the kinetic method

J Am Soc Mass Spectrom. 2009 Jan;20(1):34-41. doi: 10.1016/j.jasms.2008.09.018. Epub 2008 Sep 25.

Abstract

Stereochemical differentiation of five diastereomeric pairs of beta-amino acids, di-endo- and di-exo-2,3-disubstituted norbornane and norbornene amino acids, cis- and trans-2-aminocyclohexane-, 2-amino-4-cyclohexene-, and 2-aminocyclopentanecarboxylic acids, was investigated via the kinetic method with metal-bound trimeric complexes. This is the first time that diastereomers (di-endo/di-exo and cis/trans) have been differentiated with metal-bound trimeric complexes and the kinetic method. Moreover, determination of diastereochemical excess by the kinetic method was applied to norbornane beta-amino acids and cyclopentane beta-amino acids. Experiments showed that a remarkable differentiation of the studied diastereomers was achieved. It was observed that better selectivity values correlated to more rigid structures. The reference compounds for the studied beta-amino acids varied from alpha-amino acids to some beta-amino acids. In addition, variation of the metal ion (Cu(2+) and Ni(2+)) had some role in the selectivity values obtained. Ab initio and hybrid density functional theory calculations were performed to clarify the results obtained by mass spectrometry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Amino Acids, Cyclic / chemistry*
  • Copper / chemistry
  • Cyclohexanecarboxylic Acids / chemistry
  • Kinetics
  • Models, Molecular
  • Molecular Structure
  • Nickel / chemistry
  • Norbornanes / chemistry
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Stereoisomerism
  • Tandem Mass Spectrometry / methods*

Substances

  • Amino Acids, Cyclic
  • Cyclohexanecarboxylic Acids
  • Norbornanes
  • Copper
  • Nickel