Substituent-dependent conformational changes in 6β-substituted codeine derivatives
✍ Scribed by László Szilágyi; Sándor Makleit; Sándor Hosztafi; Csaba Simon
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 419 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Complete ^1^H and ^13^C NMR data are reported for eleven isocodeine and seven dihydroisocodeine derivatives bearing various substituents at position 6. In isocodeines having bulky succinimido or phthalimodo groups at C‐6 ring C adopts a half‐boat conformation, characterized by the quasi‐equatorial orientation of the C‐6N bond. The distortion from the usual boat form is due to steric interactions between C‐14 and β‐substituents at C‐6, and it is greater in 14‐hydroxy derivatives than in isocodeines unsubstituted at this position. In dihydroisocodeines the conformation of ring C is close to a chair, irrespective of the steric demand of the substituent at C‐6.