Europium chelates chiral shift reagents

Whitesides et al. (499) have synthesized a wide range of chiral tris-()S-diketonato)europium(iii) chelates and tested their effectiveness as chiral shift reagents. They conclude that the most effective are tris-(d,d-dicampholylmethanato)europium(iii), tris-(3-trifluoroacetyl-d-no-pinonato)europium(iii) [54], and tris-(3-trifluoroacetyl-d-cam-phorato)europium(iii), Eu(facam) [55]. It is not at present possible to... 

The enantiomers of camphorcarboxylic and sulfonic acids are used for resolution of enantiomers from racemic chiral amines and alcohols via diastereomeric salts and esters, respectively. Europium(III)- and praseodymium(III)-chelates of hydroxy-methylenecamphor derivatives are suitable chiral shift reagents for the determination of enantiomeric purity by integration of NMR spectra, because they exchange ligands with enantiomeric substrates such as alcohols and amines, thus forming diastereomeric chelates characterized by different spectra. 

The second technique is to use a chiral lanthanide shift reagent (CLSR). Addition of certain lanthanide chelates, most commonly those of europium(III), to a solution of an organic compound in CDC13 or... 

Most of the work with these metals has involved j8-diketonate chelate complexes, particular interest being shown in the use of new jS-diketonate complexes of europium(iii) and praeseodymium(iii) [e.g. tris-(l,l,l,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionato)europium(iii) and the chiral tris(perfluoroacylcamphorato) complexes (O ] as n.m.r. shift reagents (sec Chapter 3, pp. 162 and 176). 

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