Lariat ethers in the chiral recognition of amino acid esters:electrospray ionization mass spectrometry investigation

Solubility and Some Crystallization Properties of Conglomerate Forming Chiral Drug Guaifenesin in Water

“…Being really readily available in a nonracemic form, enantiomeric guaifenesin, scal ‐ 1 , could be considered as a representative of “New Chiral Pool” reagents. So starting from racemic diol rac ‐ 1 , passing through the preferential crystallization step, the following important substances have been synthesized: the chiral β‐blocker levomoprolol (used in therapy as the single S ‐enantiomer only), the drugs methocarbamol and mephenoxalone in enantiopure forms, and a family of the scalemic crown lariat ethers (Fig. ).…”

Recent advances in mass spectrometry studies of non-covalent complexes of macrocycles - A review

“…The crown ethers also have been successfully applied as chiral selectors in diverse analytical techniques like NMR and chromatographic techniques for the enantiomeric distinction of primary amines and amino acids. More direct approaches can be carried out using ESI-MS and ESI-MS/MS, for instance, direct chiral recognition based on differences in relative abundance of diasteroisomeric complexes [107], and measurements of kinetic constants for guest exchange reactions [108]. A nice example is the study of the molecular mechanisms that drive through chiral recognition between (-)-( [18]crown-6)-2,3,11,12-tetracarboxylic acid and phenylglycine (PG), threonine (Thr) and proline (Pro) [109].…”

Self-Assembled Binuclear Cu(II)–Histidine Complex for Absolute Configuration and Enantiomeric Excess Determination of Naproxen by Tandem Mass Spectrometry

“…Because of the superiority in speed, sensitivity, and specificity, mass spectrometry (MS) without chromatographic separation has attracted much interest in chiral recognition and quantification since the first report in 1977. ,, Since enantiomers show the same mass-to-charge ratio ( m / z ), chiral discrimination of enantiomers by MS relies on the introduction of a chiral selector (CS), which binds with the enantiomers covalently or noncovalently to form diastereomers. On the basis of the different behaviors of diastereomers in various MS techniques, such as their abundances in single-stage MS spectra, − dissociation efficiency in tandem mass spectrometry (MS/MS), − or drift time in ion-mobility mass spectrometry (IM-MS), , the discrimination of enantiomers could be achieved.…”