有机化学 ›› 2015, Vol. 35 ›› Issue (8): 1726-1732.DOI: 10.6023/cjoc201501034 上一篇    下一篇

研究论文

Cu(II)催化合成吡啶并[1,2-a]苯并咪唑的密度泛函理论研究

杜丽娟, 吴彩虹, 顾红红, 李娟   

  1. 暨南大学化学系 广州 510632
  • 收稿日期:2015-02-06 修回日期:2015-03-14 出版日期:2015-08-25 发布日期:2015-04-10
  • 通讯作者: 李娟 E-mail:tchjli@jnu.edu.cn
  • 基金资助:

    国家自然科学基金(No. 21103072)和中央高校基本科研业务费专项资金(No. 21615405)资助项目.

A Density Functional Theory Study of the Mechanism of Cu(II)-Catalyzed Synthesis of Pyrido[1,2-a]benzimidazoles

Du Lijuan, Wu Caihong, Gu Honghong, Li Juan   

  1. Department of Chemistry, Jinan University, Guangzhou 510632
  • Received:2015-02-06 Revised:2015-03-14 Online:2015-08-25 Published:2015-04-10
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21103072) and the Fundamental Research Funds for the Central Universities (No. 21615405).

用密度泛函方法(DFT)研究Cu(II)催化合成吡啶并[1,2-a]苯并咪唑反应的机理. 设计了5种可能的反应途径, 对各种反应的反应物、产物和过渡态的结构进行了能量梯度全优化. 通过对实验条件和实验环境的全面模拟, 得出反应首先通过协同的“金属化/去质子化”机理活化C—H, 然后在三重态上发生亚胺基去质子化, 最后经势能面交叉点S/T后还原消除(路径a). 还原消除是反应决速步.

关键词: 密度泛函理论(DFT), Cu(II)催化, C—N交叉偶联, 机理研究

The reaction mechanism of Cu(II)-catalyzed synthesis of pyrido[1,2-a]benzimidazoles was theoretically investigated with the aid of density functional theory calculations (DFT) at the B3LYP level. Five possible mechanisms for the synthesis were proposed: (1) C—H-bond-breaking step preceding deprotonation of imino group, and finally C—N bond formation (Pathway a), (2) deprotonation of imino group preceding C—H-bond-breaking step, and finally C—N bond formation (Pathway b), (3) C—H-bond-breaking as the first step, then C—N bond formation preceding deprotonation of imino group (Pathway c), (4) the anti-imino-cupration mechanism (Pathway d), (5) the Friedel-Crafts alkylation mechanism (Pathway e). The calculation results indicate that the most favorable pathway involves C—H bond breaking by concerted metalation/deprotonation (CMD), followed by N—H deprotonation along the triplet state and C—N bond formation (Pathway a). A clear understanding of the reaction mechanism of pyrido[1,2-a]benzimidazoles formation should lead to more efficient synthetic strategies.

Key words: density functional theory(DFT), Cu(II)-Catalyzed, C—N cross coupling, mechanistic study