NMR study of amphetamines using europium shift reagents.
Amphetamine and certain of its methoxylated derivatives show a high degree of interaction with NMR shift reagents of the type tris (1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione)europium(III). The shifts are not accompanied by appreciable line broadening, and both the aliphatic and aromatic protons can be resolved. The strong interaction between amine and shift reagent diminishes rapidly as the amine function is alkylated. For derivatives containing ortho-methoxyl groups, a weaker interaction with this functionality also becomes evident as the amine is alkylated. The stereospecificity of the shifting process was investigated by employing tris[3-(trifluoroacetyl)-d-camphorato]europium(III), a chiral shift reagent, with stereochemically pure enantiomers and known enantiomeric mixtures. Although certain (R)-enantiomers showed greater downfield C-methyl groups shifts, these shift differences from the corresponding (S)-enantiomers were small and not well resolved.
D000662:Amphetamines / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D005063:Europium; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008722:Methods; D008968:Molecular Conformation
D000662:Amphetamines; D005063:Europium