Chiral recognizable host-guest interactions detected by fast-atom bombardment mass spectrometry: Application to the enantiomeric excess determination of primary amines

Masami Sawada*, Yoshio Takai, Hiroyuki Imamura, Hitoshi Yamada, Shigetoshi Takahashi, Hiroshi Yamaoka, Keiji Hirose, Yoshito Tobe, Jyuichi Tanaka

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The enantiomeric excess (ee) of organic amine compounds has been determined using fast-atom bombardment (FAB) mass spectrometry based on the chiral host-guest complexation systems. The method uses a 1 : 1 mixture of the given chiral crown ether hosts (HRRRR and HSSSS-dn), one of whose enantiomers is isotopically labeled, for the ee-determination of a given amine salt guest (G+). The peak intensity ratio {I[(HRRRR + G)+] / I[(HSSSS-dn + G)+] = IRIS} of the two diastereomeric host-guest complex ions clearly changes with the change in the ee of the guest. The intensity excess (Ie) of the two complex ion peaks is newly defined as Ie = (IRIS - 1) / (IRIS + 1). The two sets of mass spectrometrically obtained Ie values vs a set of ee values of phenylalanine methyl ester and leucine methyl ester hydrochlorides show excellent linear relationships through the zero point (R2 = 0.9989 and R2 = 0.9970, respectively). This indicates the potential utility of the present ee-determination method to within ± 3% ee. Furthermore, based on the solution equilibrium distributions of the complex ions, the linearity is mathematically justified. Therefore, the ee-determination can be simplified as ee (%) = (|Ie| / |Ie(100)|) × 100: here, Ie(100) is the corresponding Ie value obtained using an enantiomerically pure (100% ee) guest as a reference. The present chiral dimethoxyphenyl crown ether host pairs employed are effective (IRIS ≥ 1.5) for the ee-determination of most α-amino acid esters, but not effective (IRIS ≈ 1.0) for most simple alkylamines.

Original languageEnglish
Pages (from-to)447-459
Number of pages13
JournalEuropean Journal of Mass Spectrometry
Volume7
Issue number6
DOIs
StatePublished - 1 Jan 2001

Keywords

  • Chiral crown ether
  • Chiral recognition
  • Deuterium labeling
  • Enantiomeric excess
  • Fast-atom bombardment
  • Host-guest complexation

Fingerprint Dive into the research topics of 'Chiral recognizable host-guest interactions detected by fast-atom bombardment mass spectrometry: Application to the enantiomeric excess determination of primary amines'. Together they form a unique fingerprint.

Cite this