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Conformational Analysis of 9,18-Difluoro-2,11-diaza[3.3]metacyclophane

Takemura, Hiroyuki ; Kariyazono, Hiroyuki ; Kon, Noriyoshi ; Shinmyozu, Teruo ; Inazu, Takahiko

Journal of organic chemistry, 1999-12, Vol.64 (25), p.9077-9079 [Periódico revisado por pares]

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Título:
Conformational Analysis of 9,18-Difluoro-2,11-diaza[3.3]metacyclophane
Autor: Takemura, Hiroyuki ; Kariyazono, Hiroyuki ; Kon, Noriyoshi ; Shinmyozu, Teruo ; Inazu, Takahiko
É parte de: Journal of organic chemistry, 1999-12, Vol.64 (25), p.9077-9079
Notas: ark:/67375/TPS-MH17VDNL-C
istex:64DE608E2CC7195D44C6BBA5FB74E211B788D88F
Descrição: The conformational isomers (syn and anti) of 9,18-difluoro-2,11-diaza[3.3]metacyclophane, 1, were isolated at ambient temperature and each was identified by 19F NMR spectra. The anti isomer gradually converted to the syn isomer in solution, and kinetic measurements of this conversion afforded the Arrhenius activation energy, E a = 24.8 ± 0.9 kcal/mol, in acetonitrile. The difference in thermodynamic stability of the syn and anti isomers in DMSO was estimated to be ca. 2 kcal/mol (298 K) on the basis of the variable temperature NMR method. The three conformational isomers, boat−boat, chair−boat, and chair−chair, are present in the syn isomer in solution. The relative stability order of the three isomers, boat−boat, chair−boat, chair−chair, is estimated by the 1H- and 19F NMR spectra. The boat−boat isomer is predominant at low temperatures, but the ratio of the other two isomers, chair−boat and chair−chair, is gradually increased as the temperature is raised.
Editor: American Chemical Society
Idioma: Inglês

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