Konformationsanalysen von pyrolytisch erzeugten [2.2]phanen des 4-Pyranons
✍ Scribed by Massa, Werner ;Schween, Michael ;Steuber, Friedrich W. ;Wocadlo, Sigrid
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1990
- Tongue
- English
- Weight
- 972 KB
- Volume
- 123
- Category
- Article
- ISSN
- 0009-2940
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✦ Synopsis
The synthesis of the first phanes of 4-pyranone is accomplished by pyrolysis of bis(su1fone) 4. Analogously, 9, 10, and 11 are synthesized. While 5 is conformationally mobile in solution, 9 and 10 are fixed (up to 100"C) and exhibit anfi conformation as shown by X-ray structural analysis (9) and computer simulation of the 'H-NMR spectra (11). Like 9 and 11, 5 exists in a staircase-like structure in the crystal. The 'H-NMR spectra of the metaparacyclophane 10 shows coalescence of the signals of the methylene protons at room temperature. The flexibility of 10 at 60°C is interpreted as a swinging process. The crystal structure of bis(su1fone) 8a shows that the two planar rings are tilted by 60" with respect to each other.
[2.2]Cyclophane mit Heterocyclen als Untereinheiten werfen bereits fur sich genommen interessante Fragen auf, z. B. zu ihrer Stereochemie und zur konformativen Beweglichkeit 'I. Sie sind aber gleichzeitig in praparativer Hinsicht iiberaus interessant, wenn, wie bei den Phanen des 4-Pyranons, die unseres Wissens bisher unbekannt sind, die vorhandenen ,,freien" oder ,,geschiitzten" Funktionalitaten vielfaltige chemische Reaktionen erlauben *) und damit zur 0