Mass spectrometry of the positionally isomeric, monobenzyl ethers of methyl glycopyranosides
✍ Scribed by Vincent Mihálov; Vladimír Kováčik; Rudolf Toman; Igor Tvaroška
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 600 KB
- Volume
- 119
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
The electron-impact, mass-spectrometric behavior of all theoretically possible, positionally isomeric monobenzyl ethers of methyl pento-, hexo-, and 6-deoxyhexo-pyranosides is described, on the basis of 70-and 12-eV mass spectra, Odcuterium-labeling experiments, elemental composition, and metastable-transition measurements.
The semiempirical MNDO quantum-chemical method was used for calculation of both the geometrical parameters (bond lengths, bond angles. and dihedral angles) and the distribution of net charges in the cyclic and acyclic forms of the abundant
[C1H703]+ and [CsH90J] + ions. The results obtained show that the cyclic structures of both ions are the more stable. Differences in the fragmentation of the compounds studied have been applied for establishing criteria that permit simple and unambiguous localization of the benzyl group in monobenzyl ethers of methyl glycopyranosides.
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extract was dried over CaCI 2 and evaporated in vacuo. The residue was purified by column chromatography [silica gel, benzene--ethyl acetate (5:1)] and recrystallized from benzene--heptane to give 1.98 g (48%) of III.
Geometric and positional isomers of the A\*-oxazoline ring system have been characterized by their mass spectral fragmentation patterns. The composition of the major ions in the spectra have been determined by high resolution mass spectrometry. A fragmentation pathway for the formation of these ions