Comparison of mass spectra of various morphine derivatives spimsric at C uc indicated the possibility of using mass spectrometry to distinguish structurally between ccmpounds hating cis-(I) and tram-(II) fusion of rings B and C.
Conformational studies on B/C-cis- and B/C-trans-morphinan derivatives
✍ Scribed by Zoltán Szabó; János Marton; Sándor Hosztafi
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 303 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
An unambiguous structural differentiation of B/C‐cis‐ and B/C‐trans‐morphinan derivatives (thebainone‐A and β‐thebainone‐A and their 7,8‐dihydro derivatives) is provided. The structures were confirmed by NOE difference spectroscopy and selective 2D J‐INEPT experiments. In addition, full a priori ^1^H and ^13^C NMR assignments of the isomeric pairs studied are presented.
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Conformational analyses of cyclic tetrapeptides consisting of alternating cis and trans peptide units have been made using contact criteria and energy calculations. This study has been restricted to those structures having a symmetry element in the backbone ring, such as a twofold axis ( d ) or a ce