Unprecedented use of 29Si NMR spectroscopy for a convenient determination of enantiomeric excesses of chiral α-C-silylated amines and alcohols†

Fortis, Fréderic; Picard, Jean‐Paul; Barbe, Bernard; Pétraud, Michel

doi:10.1039/a900491b

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…In the presence of [Eu(tfc) 3 ], a racemic mixture of α-trimethylsilylbenzyl alcohol 102 shows two separate resonances in the 29 Si NMR spectrum. This method also works well for α-trimethylsilylamines and aliphatic alcohols …”

Section: Chiral Lanthanide Complexes As Nmr Shift Reagentsmentioning

confidence: 96%

“…This method also works well for R-trimethylsilylamines and aliphatic alcohols. 156 In addition to its wide application in studying chiral organic substrates, [Eu(tfc) 3 ] can also be of use to the coordination chemist: good resolution of the Lanthanide ions are classical 'hard' Lewis acids and so generally show little propensity to bind to donors other than 'hard' O or N Lewis bases. NMR study of 'soft' chiral substrates such as alkenes therefore requires some modification to the simple chiral lanthanide shift reagent.…”

Section: Chiral Lanthanide Complexes As Nmr Shift Reagentsmentioning

confidence: 99%

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Chiral Lanthanide Complexes: Coordination Chemistry and Applications

2002

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Section: Chiral Lanthanide Complexes As Nmr Shift Reagentsmentioning

confidence: 96%

Section: Chiral Lanthanide Complexes As Nmr Shift Reagentsmentioning

confidence: 99%

Chiral Lanthanide Complexes: Coordination Chemistry and Applications

2002

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“…Baseline separation of the 29 Si peaks resulted in quite accurate determinations of the %ee's. 64 Glycoside stereochemistry is discussed in the Structure determination section.…”

Section: Determination Of Stereochemistry or Enantiopuritymentioning

confidence: 99%

12 NMR Spectroscopic methods

Halkides

McClure

2000

Annu. Rep. Prog. Chem., Sect. B

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“…226 Solution 29 Si NMR has been used in the determination of e.e. in the formation of a-silylated amines and alcohols 227 and CPMAS 29 Si was used to identify ¢ve-co-ordinate silica sites in high-silica zeolites. 228 The 1,5 sigmatropic rearrangement of silacyclopentadienes has been investigated using v.t., heteronuclear and multidimensional NMR and is found to involve a 1,2 silatropic shift.…”

Section: Scheme 19mentioning

confidence: 99%

5 Carbon, silicon, germanium, tin and lead

Parr

2000

Annu. Rep. Prog. Chem., Sect. A

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A number of review articles relevant to this chapter have appeared. The area of carbon-rich ligands has been the subject of two timely publications, a special issue of the Journal of Organometallic Chemistry 1 on carbon-rich organometallic complexes and a complementary review on cumulenylidenes. 2 The catalytic applications of metal vinylidenes 3 and the occurrence of planar carbon in organometallic complexes of group 4 and 5 elements 4 have also been reviewed. For silicon, reviews have been in the area of the formation of monolayers 5 and the chemical processing of silicon wafers. 6 A review discussing the role of p-block elements, largely tin, in determining the structure of heterometallic complexes has been published. 7 Despite the discovery of fullerenes, the newest allotrope of carbon, much interest remains in one of the older examples, diamond. The reaction of carbon tetrachloride with four equivalents of sodium metal at 973 K in the presence of a Co/Ni catalyst yields C dia . The product, identi¢ed by Raman spectroscopy, is formed as a powder in a low (ca. 2%) yield, but nevertheless this is amongst the lowest energy routes to industrial diamonds yet known. 8 The same product can be prepared using conditions designed to mimic those found on Uranus and Neptune in which methane is heated to (2^3) Â 10 3 K at pressures of 10^50 gigapascals, whereupon the methane breaks down to form diamond and polymeric hydrocarbons. 9 A convincing argument has been presented for the formation of such a dense solid from a light gaseous phase contributing to the internal heat, magnetic ¢eld and luminosity of a celestial body, and hence the possible signi¢cance of this process in planet formation. A report of the synthesis and identi¢cation of C 6 CH 2 as :C( C C) 2 C CH 2 by removal of the charge from the C 6 CH 2 À. radical anion during neutralisationreionisation mass spectroscopy has been published and related to the cumulenes found in circumstellar dust. 10 Cumulene complexes of transition metals continue to attract much attention. Although synthetic protocols are well established, some new approaches have appeared outlined in Scheme 1. 11,12 The last compound shown is a very rare example of a linear ten atom chain C 8 Rh 2 . Cumulenes with extremely long carbon chains have also appeared, such as 3 which shows in the solid state a distinct twisting of the C 12 chain away from linear, 13 and 4 and 5 (Scheme 2). The crystal structure of 5 shows C^C bond lengths of 1.210^1.233 Ð for triple bonds

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Unprecedented use of 29Si NMR spectroscopy for a convenient determination of enantiomeric excesses of chiral α-C-silylated amines and alcohols†

Cited by 7 publications

References 22 publications

Chiral Lanthanide Complexes: Coordination Chemistry and Applications

Chiral Lanthanide Complexes: Coordination Chemistry and Applications

12 NMR Spectroscopic methods

5 Carbon, silicon, germanium, tin and lead

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