作者:Trevor A. Crabb、Andrew N. Trethewey、Yoshito Takeuchi
DOI:10.1002/mrc.1260260413
日期:1988.4
Low-temperature 13C and 1H NMR spectra show perhydrooxazolo[3,4]-apyridine to exist in CDCl3CFCl3 solution at 183 K as an equilibrium between 73% trans-fused and 27% O-inside cis-fused conformers. cis-(H-1, H-8a)-1-Alkylperhydrooxazolo-[3,4-a]pyridines (alkyl = methyl, ethyl, isopropyl) adopt equilibria heavily biased towards the trans-fused conformers, whereas the epimers adopt 18% O-inside cis-fused = 82% trans-fused comformational equilibria at 183 K in CDCl3CFCl3. At 190 K in CDCl3 cis-(H-6, H-8a)-6-ethylperhydrooxazolo[3,4-a]pyridine adopts an equilibrium containing ca 3% trans-fused conformer in equilibrium with 97% O-inside cis-fused conformer.
低温 13C 和 1H NMR 光谱显示,在 183 K 时,全氢恶唑并[3,4]-吡啶在 CDCl3CFCl3 溶液中存在 73% 的反式融合构象和 27% 的 O 内顺式融合构象之间的平衡。在 183 K 的 CDCl3CFCl3 溶液中,顺式-(H-1, H-8a)-1-烷基全氢噁唑并-[3,4-a]吡啶(烷基=甲基、乙基、异丙基)采用严重偏向于反式融合构象的平衡,而表聚物则采用 18% O-inside 顺式融合 = 82% 反式融合的构象平衡。在 190 K 的 CDCl3 中,顺式-(H-6, H-8a)-6-乙基全氢恶唑并[3,4-a]吡啶采用了一种平衡,其中包含约 3% 的反式融合构象与 97% 的 O-inside 顺式融合构象。