1H and 13C NMR
Europium shift reagent
Analytical Chemistry and Spectroscopy
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The enantiomeric purities of disubstituted β-lactams were determined by 1H and 13C NMR spectroscopy using tris[3-(trifluoromethylhydroxymethylene)-d-camphorato]europium(III), Eu(tfc)3, as a chiral shift reagent. Using a [Eu(tfc)3]/[lactam] ratio of 0.5, most of the resonances were split into signal pairs due to the respective enantiomers. The method gives quantitative enantiomeric compositions. 13C NMR spectroscopy is more advantageous than 1H NMR, which is of limited use owing, for example, to the significant line broadening observed in the 1H spectra at [Eu(tfc)3]/[lactam] 〉 0.8. Assignments of the proton and carbon signals were obtained for the two enantiomers of the complexed lactams.
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