## Abstract The conformational analysis of three 1,2โ3,4โdiโ__O__โMethylenepyranoses was carried out using NMR (coupling constants and homonuclear Overhauser effect) and theoretical (MM2 calculations) methods. A preferred twistโboat conformation was found.
An NMR study of the conformational equilibrium of 5-fluoro-1,3-dioxan in solution. Dependence on solvent
โ Scribed by L. D. Hall; R. N. Johnson
- Publisher
- John Wiley and Sons
- Year
- 1972
- Tongue
- English
- Weight
- 490 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0749-1581
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โฆ Synopsis
The 'H and IBF NMR parameters of 5-fluoro-1,3-dioxan (1) dissolved in a number of solvent systems are interpreted on the basis of fast inversion between two chair conformations. In cyclohexane solution the two chair conformations are almost equally populated, whereas in more polar solvents, such as chloroform, the conformation having the fluorine substituent in an axial position is strongly preferred. Addition of acetic acid to a solution of 1 in cyclohexane increases the preference of the fluorine substituent for the axial orientation. Possible reasons for these observations are discussed. I N T R O D U C T I O N * See Ref. 1.
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