物理化学学报 >> 2015, Vol. 31 >> Issue (5): 852-858.doi: 10.3866/PKU.WHXB201503026

理论与计算化学 上一篇    下一篇

铁催化芳基格氏试剂的联芳交叉偶联的反应机理

任清华, 沈晓燕   

  1. 上海大学理学院化学系, 上海200444
  • 收稿日期:2014-12-25 修回日期:2015-02-09 发布日期:2015-05-08
  • 通讯作者: 任清华 E-mail:qinghua.ren@shu.edu.cn
  • 基金资助:

    上海大学高性能计算平台"自强4000"与上海市高等教育内涵建设"085"工程"材料基因工程"项目(B.58-B111-12-101, B.58-B111-12-103)资助

Reaction Mechanism for the Iron-Catalyzed Biaryl Cross-Coupling of Aryl Grignard Reagents

REN Qing-Hua, SHEN Xiao-Yan   

  1. Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, P. R. China
  • Received:2014-12-25 Revised:2015-02-09 Published:2015-05-08
  • Contact: REN Qing-Hua E-mail:qinghua.ren@shu.edu.cn
  • Supported by:

    The project was supported by the High Performance Computing Platform of Shanghai University, China and Shanghai Higher Education Connotation Construction"085"Project"Materials Genome Engineering"Funding, China (B.58-B111-12-101, B.58-B111-12-103).

摘要:

利用密度泛函理论(DFT)计算研究了[Fe(MgBr)2]催化的邻氯苯乙稀与溴代苯基镁反应生成联芳化合物的交叉偶联反应的机理. 研究了两个机理. 机理A包括三个基本步骤: (I) 氧化[Fe(MgBr)2]生成[Ar-Fe(MgBr)],(II) 加成产生[Ar-(phenyl)-Fe(MgBr)2], (III) 还原消除回到[Fe(MgBr)2]. 机理B不形成[Ar-Fe(MgBr)]. 在第一步,溴代苯基镁在[Cl-Mg-Br]离解形成[Ar-Fe(MgBr)]之前直接进攻氧化加成后的中间体. 考虑溶剂效应后, 机理B优于机理A. 无论机理A还是机理B, 整个催化循环过程的决速步骤都是[Ar-(phenyl)-Fe(MgBr)2]的还原消除再生催化剂[Fe(MgBr)2]的步骤, 使用导体极化连续模型(CPCM)方法计算其在四氢呋喃溶剂中的吉布斯自由能(ΔGsol)是82.98 kJ·mol-1.

关键词: 铁催化剂, 联芳, 交叉偶联, 反应机理, 密度泛函理论

Abstract:

Mechanisms for the [Fe(MgBr)2] catalyzed cross-coupling reaction between ortho-chlorostyrene and phenylmagnesium bromide to form biaryl were studied using density functional theory (DFT) calculations. We investigated two mechanisms. Cycle A included three basic steps: (I) oxidation of [Fe(MgBr)2] to obtain [Ar- Fe(MgBr)], (II) addition to yield [Ar-(phenyl)-Fe(MgBr)2], and (III) reductive elimination to return to [Fe(MgBr)2]. Cycle B did not form [Ar-Fe(MgBr)]. In the first step, phenylmagnesium bromide attacks the intermediate of the oxidative addition directly before [Cl-Mg-Br] dissociates to form [Ar-Fe(MgBr)]. The catalytic Cycle B is favored over the catalytic Cycle Awhen considering the solvent effect. The rate-limiting step in the overall catalytic cycle for both Cycle A and Cycle B is the reductive elimination of [Ar-(phenyl)-Fe(MgBr)2] to regenerate the catalyst [Fe(MgBr)2], where the Gibbs free energy in solvent tetrahydrofuran (THF), ΔGsol, is 82.98 kJ ·mol-1, as determined using the conductor polarized continuum model (CPCM) method.

Key words: Iron catalyst, Biaryl, Cross-coupling, Reaction mechanism, Density functional theory

MSC2000: 

  • O641