Chiral (2-cyanophenoxy)methyl-15-crown-5 in diastereomeric discrimination of amino acid esters according to the data of electrospray ionization mass spectrometry

Abstract

The ability of [(2-cyanophenoxy)methyl]-15-crown-5 lariat ether enantiomers to diastereomeric discrimination with respect to hydrochlorides of 1-phenylethylamine and methyl esters of alanine, phenylalanine, and phenylglycine was studied by electrospray ionization mass spectrometry. The mentioned crown ether is available in non-racemic form owing to the procedure of preferential crystallization of enantiomers of its precursor. The quantitative estimation of the differences in the formation of diastereomeric complexes between the crown ether and the guests was performed by two independent methods: application of the guests with isotopic markers and using an additive of achiral amine-displacer. Both approaches indicate the existence of a moderate chiral discrimination: The (S)-enantiomer of the crown ether binds prevailingly the (S)-enantiomer of the guest, and vice versa.