新型环戊二烯基配体的双功能催化模式研究

新型配体的不断开发是过渡金属催化领域发展的主要动力。传统的环戊二烯基配体类催化体系在C–H键官能团化领域的发展长期局限于配位导向模式所造成的单一选择性问题。本项目计划将静电弱相互作用引入到该催化体系中，以双功能催化模式探索羧酸类化合物的远程C–H键胺化反应，力争突破传统催化模式在反应区域选择性上的局限性。本项目将合成一系列不同类型、不同位阻大小以及不同电荷密度分布的含正电荷环戊二烯基配体（Cpx+）及相应过渡金属催化剂，通过对Cpx+配体结构的调节来实现其与底物（羧酸负离子）之间静电弱相互作用的调控，从而影响反应过渡态优势构象，进而获得传统配位导向模式难以实现的远程C–H键胺化选择性。在此基础上，开展对结构种类丰富多样的羧酸类天然产物和药物分子的多位点C–H键胺化反应研究。最终，建立起一系列以高度可控的静电弱相互作用为特色的新型双功能环戊二烯基类催化体系，为该领域的持续发展提供新的动力。

The history of transition-metal catalysis has long been driven by ligand design. The C–H functionalization methods catalyzed by cyclopentadienyl-metal complexes are facing the challenge of limited regioselectivity controlled by the conventional chelating directing effect. In this project, electrostatic interaction will be introduced to address the issue of regiocontrol in the C–H amination of carboxylic acids. A range of novel cyclopentadienyl ligands (Cpx+) containing different types of positively charged substitutions and the corresponding transition metal complexes will be synthesized for the investigation of our electrostatic-directed approach towards anionic carboxylic substrates. It could be anticipating that the electrostatic interaction would be tuned by modifying the structure of charged cyclopentadienyl ligands, so the conformation of transition states could be modulated in order to achieve unconventional regioselectivities. Moreover, the C–H amination of various carboxylic acid-containing natural products and drugs will also be studied. Ultimately, we’re going to build up a unique bifunctional cyclopentadienyl ligand-based catalytic system featuring the highly tunable electrostatic interaction, which could be envisioned for wider application in more regioselective transformations.