The investigation of stereogenic properties of cyclotriphosphazene derivatives with two different chiral centres

Hexachlorocyclotriphosphazene N3P3Cl6 and gem-disubstituted cyclotriphosphazene derivatives N3P3Cl4X2 (X = Ph, PhS, PhNH) were reacted with N-methyl-1,3-propanediamine and 3-amino-1-propanol to give compounds (9a–12a, 9b–12b) which exist as cis and trans geometric isomers and are two different racemic isomers, respectively to describe the stereogenic properties of a series of chiral cyclotriphosphazene compounds with two different centres of chirality. The geometric isomers were separated by column chromatography on silica gel and analysed by elemental analysis, mass spectrometry, and 31P and 1H NMR spectroscopies, and also the geometric forms (cis or trans) of 9b, 10a, 11a, 11b and 12a have been determined by the X-ray crystallography. The enantiomers of all racemic compounds have been analysed by the changes in 31P NMR spectra on addition of a Chiral Solvating Agent (CSA), (R)-(+)-2,2,2-trifluoro-1-(9′-anthryl)ethanol. On the other hand, the racemic forms of chiral cyclotriphosphazene derivatives have been confirmed by contribution of chiral HPLC methods which have been developed for this study.

Graphical abstractIn this paper, the synthesis, characterization and investigation of phosphazene compounds with two different stereogenic centres, N3P3X2[HN(CH2)3NMe][O(CH2)3NH] (X = Cl, Ph, PhS, PhNH), have been reported for the first time.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Phosphazene derivatives with two different stereogenic centres have been synthesized. ► Their characterization have been made by spectroscopic techniques. ► The stereogenic properties of compounds have been investigated by NMR, and X-ray. ► The racemic forms of phosphazene derivatives have been confirmed by chiral HPLC.