Nuclear Magnetic Resonance Spectroscopy for Structure Elucidation of Vitamin B12 Derivatives: Complete Interpretation of the13C-NMR Spectrum of Dicyanocobyrinic Acid Heptamethyl Ester and Partial Assignment of Its1H-NMR Spectrum
✍ Scribed by Ernst, Ludger
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 537 KB
- Volume
- 1981
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
The ^13^C‐NMR chemical shifts of dicyanocobyrinic acid heptamethyl ester (1), an important corrinoid model compound, are correlated with those of some derivatives. Isotope effects on the ^13^C chemical shifts (over two to four bonds) are observed for the 10‐deuterio and the 10,13‐dideuterio analogues 4 and 5 of 1. The effect of the deuterium at C‐13 in 5 upon the two 12‐methyl groups is stereospecific. Together with spin‐lattice relaxation times, these informations allow the complete interpretation of the ^13^C‐NMR spectrum of 1 (apart from the ester methyl resonances of sidechains a to f, which all absorb within a range of 0.3 ppm). The ^1^H‐NMR spectrum of 1 is partly assigned via selective ^13^C{^1^H}‐double resonance.