波谱学杂志 ›› 2008, Vol. 25 ›› Issue (3): 307-314.

• 研究论文 • 上一篇    下一篇

吡啶酰胺类化合物中酰胺键异构化的变温核磁共振研究

乔瑞瑞; 孙静; 杨春晖; 肖强; 崔育新   

  1. (北京大学药学院,天然药物与仿生药物国家重点实验室,北京 100083)
  • 收稿日期:2007-11-20 修回日期:2008-03-19 出版日期:2008-09-05 发布日期:2009-12-05
  • 通讯作者: 崔育新

Isomerization of the Amide Bond in Piperidin Amides Studied by Variable-temperature NMR Spectroscopy

QIAO Rui-rui; SUN Jing; YANG Chun-hui; XIAO Qiang; CUI Yu-xin   

  1. (State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100083, China)
  • Received:2007-11-20 Revised:2008-03-19 Online:2008-09-05 Published:2009-12-05
  • Contact: Cui Yu-xin

摘要: 合成了一系列六氢吡啶酰胺化合物以研究酰胺键的双键性质. 采用1H 及13C NMR 技术确证了不同取代的酰胺化合物中酰胺键的双键性质. 进一步采用变温核磁共振技术对2-(3,5-dinitrophenyl)-1-(piperidin-1-yl)ethanone(化合物1)进行了1H 及13C NMR研究. 结果表明,在20 ℃(293 K)时,a, b及c, d上的氢和碳原子具有不同的化学位移,且距酰胺键越近,化学位移的差异越大. 随着温度的升高,两种异构体的转换速率增加,酰胺双键的性质越来越不明显,导致化学位移的差异逐渐减小,直至融合为一个峰. 经计算,在融合温度下两种异构体的相互转换的速率常数是380 s-1,能垒约为67 kJ• mol-1. 

关键词: 核磁共振, 变温核磁, 酰胺键, 异构体

Abstract: A series of amides of piperidin were synthesized and used for studies on the partial doublebond feature of the amide bonds. 1H and 13C NMR spectra of 2-(3, 5-dinitrophenyl)-1-(piperidin-1-yl) ethanone (compound 1) were acquired at various temperatures. The results showed that the C-N bond of the piperidin amides exhibited partially double-bond character at 20 ℃ (293 K) , suggesting that the chemical shifts of a and b, c and d in compound 1 were very- different due to the two rotameric states. With increasing temperature, the two peaks of non-equivalent -CH2- groups collapsed into one peak due to the fast rotation of the C-N bond. The rate constant for the dynamic process detected for compound 1 was 380 s-1, and the free energy of activation for compound 1 at coalescence temperature (343 K) was 67 kJ · mol-1.

Key words: NMR, variable-temperature experiment, amide bond, isomerization

中图分类号: