The Kagan amide, (R)-<i>N</i>-(3,5-dinitrobenzoyl)-α-phenylethylamine, is a known chiral solvating agent (CSA) for the 1H NMR spectral resolution of enantiomers containing diverse functional groups such as alcohols, amides, amines and sulfoxides. Until now, the thio- and seleno- amide variants of the Kagan amide have not been reported in the literature. In this talk, we describe the synthesis of these two congeners from commerically available Lawesson's organosulfur or Woollin's organoselenium reagents. These molecules were then tested as CSAs against a panel of amides analytes derived from racemic α-methylbenzylamine through NMR titration experiments. The acyl moiety of the analyte amide was found to significantly impact the spectral resolution of the enantiomers as observed by the ΔΔδ value defined by ΔδS - ΔδR. Furthermore, x-ray analysis of a single crystal of a CSA-analyte bound complex offers insight into the non-covalent interactions responsible for the observed chemical shift inequivalencies.

Investigation of thioamide variants of the Kagan amide as a chiral solvating agent for the differentiation of α-methylbenzylamides by <sup>1</sup>H NMR spectroscopy

ACS Spring 2022

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Investigation of thioamide variants of the Kagan amide as a chiral solvating agent for the differentiation of α-methylbenzylamides by 1H NMR spectroscopy

Investigation of thioamide variants of the Kagan amide as a chiral solvating agent for the differentiation of α-methylbenzylamides by ¹H NMR spectroscopy