...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Química Nova >Efeito da substitui??o por átomos de flúor no equilíbrio conformacional de chalcona
【24h】

Efeito da substitui??o por átomos de flúor no equilíbrio conformacional de chalcona

机译：氟原子取代对查尔酮构象平衡的影响

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Chalcone (1) and its fluorinated derivatives 2-4, as well as their cyclic analogues 5-10, were synthesized through an aldol condensation reaction between the corresponding ketone and aldehyde. These compounds were characterized by IR, EIMS and 1H and 13C NMR spectral data. Modern NMR techniques allowed us to conclude that the compounds obtained show E configuration. These techniques were also employed to investigate the equilibrium involving the s-cis and s-trans conformations of 1-4, with this equilibrium being dependent on the fluorine substitution on both aromatic rings, A or B. IR studies indicated that the yield of the s-cis conformation in the fluorinated derivatives is 57.4±1.4; 88.1±0.4 and 66.4±0.7%, for 2, 3 and 4, respectively, based on previous 1H NMR calculations for chalcone. Theoretical calculations, using the MMX method, were employed to justify the variation of chemical shifts for the fluorinated derivatives and cyclic analogues. These chemical shifts are consequence of the anisotropic effect showed by the carbonyl group on these compounds.
机译：查尔酮（1）及其氟化衍生物2-4及其环状类似物5-10是通过相应的酮与醛之间的羟醛缩合反应合成的。这些化合物的特征在于IR，EIMS，1H和13C NMR光谱数据。现代NMR技术使我们得出结论，即所获得的化合物显示E构型。还使用这些技术研究了1-4的s-顺式和s-反式构象的平衡，该平衡取决于两个芳环A或B上的氟取代。IR研究表明，氟化衍生物中的s-顺式构象为57.4±1.4。根据查尔酮的先前1H NMR计算，对于2、3和4，分别为88.1±0.4和66.4±0.7％。使用MMX方法进行理论计算，以证明氟化衍生物和环状类似物的化学位移变化是合理的。这些化学位移是羰基对这些化合物表现出的各向异性作用的结果。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号