研究室工作进展 Apr. 23rd, 2013.
1,2,3,4-Tetrasubstituted Cyclopentadienes and Their Applications for Metallocenes: Efficient Synthesis via Zirconocene and CuCl Mediated Intermolecular Coupling of Two Alkynes and One Diiodomethane
Weizhi Geng, Chao Wang, Jie Guang, Wei Hao, Wen-Xiong Zhang, Zhenfeng Xi*
Chem. Eur. J. 2013, DOI: 10.1002/chem.201300416
1,2,3,4-Tetrasubstituted cyclopentadienes and indene derivatives with identical or different substituents, were obtained in good to excellent isolated yields via a zirconocene and CuCl mediated intermolecular coupling process. This synthetic procedure involved three organic partners including one CH2I2, and two different or identical alkynes. Two alkynes or one diyne undergo Cp2Zr(II)-mediated pair-selective reductive coupling to afford their corresponding zirconacyclopentadiene derivatives, which react, in the presence of CuCl and DMPU, with CH2I2 via intermolecular followed by intramolecular coupling to afford the cyclopentadiene derivatives. Application of thus prepared tetra-substituted cyclopentadiene derivatives was demonstrated by the facile synthesis of their corresponding zirconocene complexes (4RCp)2ZrCl2, (4RCp)2ZrMe2, (4RCp)2ZrEt2 and (4RCp)2ZrBu2. The unique 1,2,3,4-tetrasubstituted cyclopentadiene ligands and their corresponding metallocenes are expected to have further applications in organometallic chemistry and organic synthesis.
背景介绍
配体是过渡金属催化合成化学的核心之一。设计、合成具有独特结构和自主知识产权的配体是本研究室长期以来的工作目标之一。本研究室十余年来发展了数个合成多取代环戊二烯以及杂环骨架化合物的新方法。在此基础上，我们开展了新型配体及其过渡金属配合物的合成、催化应用与机理研究。例如，我们利用自己发展的方法，以及合成了三类配体：1）含有长链烷基的多取代环戊二稀配体；2）分子内含有多取代环戊二烯（双烯）以及磷原子的新型膦-双烯配体；3）含有多取代环戊二烯阴离子和氧负离子的多齿配体（简称OCp双负离子配体）。目前本研究室的相关研究主要集中在基于以上三类配体的过渡金属催化反应的应用研究及机理探讨。本论文工作（由王超同学于2006年首先尝试）建立了合成1,2,3,4-四取代环戊二烯的有效方法。由于该类环戊二烯的独特取代模式，其作为配体与过渡金属配合预期将有独特作用。