1H NMR Spectral Simplification with Achiral and Chiral Lanthanide Shift Reagents. IV. Metaxalone, 5-(3,5-Dimethylphenoxymethyl)-2-oxazolidinone; Evidence for Multidentate Chelation |
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Authors: | Alexander Hatzis Robert Rothchild |
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Institution: | The City University of New York Toxicology Research and Training Center John Jay College of Criminal Justice, Department of Science , 445 West 59th Street, New York, NY, 10019-1199 |
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Abstract: | The 60 MHz 1H NMR spectra of racemic metaxalone, 1, have been studied in CDC13 solution at 28° with the achiral shift reagent tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato)europium(III), 2, and the chiral reagents tris3-(trifluoromethylhydroxymethylene)-d-cam-phorato]europium(III), 3, and tris3-(heptafluoropropylhydroxymethylene)-d-camphorato]europium(III), 4. Reagent 3 produced modest observable enantiomeric shift differences, ΔΔδ, for the CH20, aryl methyl, aryl H2,6 and the NH siqnals. Although reaquent 4 produced small or no observable ΔΔδ for the CH20, aryl methyls or aryl protons. strikingly qreater valuesof lanthanide induced shift, Δδ, as well as ΔΔδ, were found for the NH signal using 4 relative to 3. Analytical feasibility for direct optical purity determinations of 1 with 0 using this NH siqnal sclould allow detection of 74% of the minor enantiomer or less. Results are discussed ir terms of potential bidentate or tridentate chelation of 3 by 1 makinrl a greater contribution than for 4. |
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