1H-NMR.-spektroskopische Analyse von prochiralen Allencarbonsäureestern mit optisch aktiven Europium-Verschiebungsreagenzien
✍ Scribed by Robert W. Lang; Hans-Jügen Hansen
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- German
- Weight
- 429 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
^1^H‐NMR. Spectroscopic Analysis of Prochiral Allenic Esters Using Optically Active Europium Shift Reagents
The prochiral allenic methyl esters 1–4 (cf. Scheme) show in the presence of 1 mol‐equiv. tris[3‐(heptafluorobutyryl)‐(+)‐camphorato]europium (III) (Eu (hfc)~3~) in 1,1,2‐trichloro‐1,2,2‐trifluoroethane (TCFE) induced unlike ^1^H‐NMR. shift differences (ΔΔδ) for the enantiotopic protons and methyl groups on C(4), respectively (cf. Fig. 2 and 3). This effect allows to determine directly the ^2^J~H,H~ coupling constants of the geminal protons on C(4) of the allenic esters 1 (15.5 Hz) and 2 (14.5 Hz) (cf. Table 2).