金属铱配合物的合成及其催化的C-F活化与C-H活化竞争反应研究

Transition metal catalyzed C-H bond and C-F bond activation reactions are currently the frontier areas in transition metal catalysis and have attracted broad interests among organic synthesis, pharmaceuticals, materials and agrochemical sciences. Although each of them has achieved great progress, reports concerning the intrinsic relationship between transition metal catalyzed C-H bond and C-F bond activation reactions and the competition between them in some important reaction systems are still lacking. In some complex substrates where both C-H and C-F bond activation reactions might occur simultaneously, to achieve the desired C-H activation or C-F activation reactions by means of tuning the reaction conditions, especially the catalyst and the ancillary ligands has been growing into an urgent challenge. In this context, we will systematically study the mechanisms for iridium-catalyzed C-H activation and C-F bond activation reactions, their intrinsic relationships and competition principles based on our preliminary studies on iridium mediated C-H activation and C-F activation reactions. Novel model reactions systems will be designed to study iridium-catalyzed C-H and C-F activation mechanisms and their relationships through capture of some key intermediates, kinetic studies and theoretical calculations. Subsequently, competition studies between iridium-catalyzed C-H and C-F bond activation reactions will be conducted, with the emphasis on the catalyst effect, ancillary ligand effect and substituents effects, which should lead to conceptually important transition metal-catalyzed chemoselective C-H or C-F bond activation reactions. These studies should provide valuable information for the understanding, development and tuning of transition metal-catalyzed C-H and C-F bond activation reactions and pave the way for their advanced applications in complex organic synthesis.

过渡金属配合物催化的C-H活化和C-F活化反应是近年来的前沿热点研究领域，它们在有机合成、药物学、材料学以及医（农）药化学等领域中有重要的应用。尽管过渡金属催化的C-H活化或C-F活化各自本身都已经取得了较大的进展，但是关于它们之间的内在联系以及它们之间的竞争规律目前还缺乏了解。在一些底物中，有可能同时发生C-H活化和C-F活化反应，如何有效地控制反应的条件，特别是催化剂和配体等，来实现所需要的C-H活化或C-F活化反应便成为了一个急需解决的科学问题。本研究拟通过设计选择新颖巧妙的反应体系、合成捕获反应中间体、理论计算热力学和动力学过程等，研究铱配合物催化的C-H活化和C-F活化的具体机理路径，以及在此基础上的竞争性规律。着重从铱配合物催化剂、配体和取代基效应等方面进行深入的分析。研究结果将为国内外相关学者理解过渡金属催化的C-H活化或C-F活化反应提供基础数据。

本项目首先从实验和反应机理两方面研究了金属铱配合物对C-H和C-F的催化活化作用以及配体（取代基）、添加物对催化作用的影响，结果表明：(1)导向基团、膦配体和硼配体（或添加物）与金属配合物的协同效应在催化过程中发挥了关键作用；(2) 金属铱氢化合物存在于反应过程中；(3) 金属铑的催化活性高于金属铱。.初步研究了中间体金属氢化物在偶联反应以及在C-F活化反应中作为氢源（去氟氢化）的应用。协同效应的进一步研究表明，C-F活化反应可以在没有过渡金属存在下发生选择性C-F键断裂。.苯基吡啶衍生物在过渡金属的催化下可以发生C-H活化反应，更惰性的氟代苯基吡啶衍生物中的C-F键在协同效应作用下可以在过渡金属催化下发生C-F活化反应，也可以在没有过渡金属下发生选择性反应。.本项目通过对C-H活化和C-F活化的研究，不仅进一步地认识了C-H活化和C-F活化的基本规律，也为有关化合物的合成提供了新途径。