Tris europium spectroscopy

Reaction of the chiral lithium enolate of meso-2,6-dimethylcyclohexanone (6), generated by deprotonation with (R)-l-phenylethylamine and (/ )-camphor/(R)-l-phenylethylaniine derived chiral lithium amides (Table 1, entries 17 and 64) with 3-bromopropene, leads to homoallyl ketones of opposite absolute configuration in acceptable yield with poor to modest enantiomeric excess14, which can be determined directly by H-NMR spectroscopy in the presence of tris [3-(heptafluorohydroxymethylene)-D-camphorato]europium(III) [Eu(hfc)3]. 

Chauvin, A.-S., Gumy, F., Imbert, D., and BunzU, J.-C.G (2004) Europium and terbium tris(dipicolinates) as secondary standards for quantum yield determination. Spectroscopy Letters, 37 (5), 517-532. 

There is the potential with some substrates that the Lewis acidity of the lanthanide ion can catalyze a reaction. For example, the addition of Eu(hfc)3 to a racemic mixture of dimethylpenta-2,3-dienoates (39) caused an enrichment of the (5 )-isomer °. Over nine days the mixture converted to an 89 11 mixture. Lanthanide tris( S-diketonates) are well known catalysts for Diels-Alder reactions, and NMR spectroscopy of the reactants with Eu(hfc)3 was used to understand the stereoselectivity of the europium-catalyzed cycloadditions . ... 

---