Europium shift reagents

Europium (III) acetate (2H2O) [62667-64-5] M 383.1, pKj 8.31 (for aquo Eu " ). Recrystd several times from water [Ganapathy et al. J Am Chem Soc 108 3159 1986]. For europium shift reagents see lanthanide shift reagents in Chapter 4. 

The use of Europium shift reagent in combination with EDTA was used to study chelation to phospholipids.60... 

Europium shift reagents see lanthanide shift reagents. 

The proton NMR spectrum of 1,10-phenanthroline has been obtained and analyzed by several authors in nonaqueous solvents 04-109 and in water at various pH values.28,110 Examples of studies of the NMR spectra of substituted 1,10-phenanthrolines that have been investigated in some detail are also worthy of mention.47,104,106,11° The NMR spectra of all ten phenanthrolines have been determined in deuterochloroform, and the spectra were interpreted12 (Table IV). The spectra of the 1,7-, 1,10-, and 4,7-isomers have also been compared with that of phenanthrene.111 Shifts in the NMR spectrum of 1,10-phenanthroline induced by a europium shift reagent have been discussed,112 and 13C chemical shifts of free and protonated 1,10-phenanthroline were measured.113... 

Dipolar cycloaddition of the sodium salt of cyanoacetamide or mal-ononitrile to the acetonide of racemic or optically active l-azido-2,3-dihydroxypropane 290 afforded the intermediate triazoles 291, which were converted directly to the 2-substituted 9-(2, 3 -dihydroxypropyl-8-azahypoxanthines 294 and 8-azaadenines 295 by treating with a suitable ester or nitrile to give the isopropylidene derivatives 292 and 293, respectively, followed by acid hydrolysis. The percentage of racemization was determined by NMR with the Europium shift reagent [Eu(tfc)3] (91JHC1351) (Scheme 58). 

Certain transition metal complexes exhibit activating properties and act with turnover on the metal center analogously to the catalytically active zinc ion in the active center of liver alcohol dehydrogenase. Various chiral europium shift reagents, for example Eu(hfc)3, induce reduction of (9b) by 1,4-dihydroni-cotinamides. Turnovers of about 100 are obtained on the metal complexes and methyl mandelate is formed with enantiomeric excesses of 25-44%. ... 

Cleaning Up Place the contents of the nmr tube in the europium shift reagent hazardous waste container. 

Then we changed over to the isomer allylic alcohol, to 3-methyl-2-buten-l-ol (prenol). Being a primary alcohol, it was smoothly epoxidized under both stoichiometric and catalytic Sharpless conditions. While the stoichiometric method provides only moderate yields as the dimethyl glycidol is fairly watersoluble, the catalytic method affords the double yield. The e.e. amounts to 90% in both cases. Optical purity and e.e. of the 3,3-dimethyl glycidol were determined by polarimetry and -NMR in the presence of chiral europium shift-reagent [22]. 

Figure 2.6. A predictive model of the equilibria between diastereo-meric Mosher esters and a europium shift reagent.

The n.m.r. spectrum of reserpine in the presence of the europium shift reagent is interpreted" in terms of a boat-shaped conformation of ring c. 

Location of the methoxy group at C-12 was determined from the PMR spectrum in the presence of a europium shift reagent. 

Hetero Diels-Alder reactions are a good entry for the preparation of intermediates for total synthesis of sugars. The lanthanide catalysts allow to work with labile reactants and adducts with an excellent stereo-chemical control. Moreover Danishefsky found (56) that a chiral europium shift reagent (Eu(hfc) ) is able to catalyze asymmetric cycloaddition (eq. 40] ). ... 

In this experiment, you will use the chiral europium shift reagent 17 to determine the enantiomeric excess of the product that you obtained upon enantioselec-tive reduction of methyl acetoacetate with baker s yeast. 

Which of the following compounds will form diastereomeric complexes with the chiral europium shift reagent 17 ... 

Tris(pivalomethanato)europium shift reagent has been used in the interpretation of the n.m.r. spectra of a variety of epoxides and the epoxide concentration, rather than the mole ratio of the shift reagent to the epoxide, is shown to be the most important factor in obtaining resolution. A method of distinguishing between meso- and //-diastereomers, using either chiral solvents or lanthanide shift reagents, has been applied to epoxides for example dieldrin (13) was confirmed as meso. 

A report of the n.m.r. spectra of some five-member ring phosphites and related compounds is interpreted in terms of their probable conformations. Europium shift reagents have been used by two groups to simplify the n.m.r. spectra of some 2-alkyl-2-oxo-l,3,2-dioxaphosphorinans (50) and (51). The American group showed that increasing the amount of... 

Chemists did not follow the caution voiced by Weissman [30] that both contact and pseudocontact (dipolar) shifts are to be expected in molecules coordinated to Europium shift reagents. Numerous workers applied a simplified form of the McConnell Robertston relationship (Equation (3)) for pseudocontact interaction as the sole interpreter of the lanthanide induced shifts in rigid organic molecules. It has been shown that especially when C data are compared to H data [31], that both the dipolar and contact effects operate simultaneously ... 

The proton n.m.r. spectra of some 3,6-anhydro-D-galactose derivatives in the presence of a europium shift reagent showed that the shift reagent had a strong affinity for these derivatives. This phenomenon could be used to analyse for residues of 3,6-anhydro-o-galactose or its enantiomorph in agar-and carrageenan-like polysaccharides. 

The quantitative determination of the Xe content in liquids using NMR spectroscopy has been described. A chiral europium shift reagent has been used for Xe complexed by cryptophane-A. Xe NMR spectroscopy has... 

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