研究室工作進展 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.
背景介紹
配體是過渡金屬催化合成化學的核心之一。設計、合成具有獨特結構和自主知識産權的配體是本研究室長期以來的工作目标之一。本研究室十餘年來發展了數個合成多取代環戊二烯以及雜環骨架化合物的新方法。在此基礎上，我們開展了新型配體及其過渡金屬配合物的合成、催化應用與機理研究。例如，我們利用自己發展的方法，以及合成了三類配體：1）含有長鍊烷基的多取代環戊二稀配體；2）分子内含有多取代環戊二烯（雙烯）以及磷原子的新型膦-雙烯配體；3）含有多取代環戊二烯陰離子和氧負離子的多齒配體（簡稱OCp雙負離子配體）。目前本研究室的相關研究主要集中在基于以上三類配體的過渡金屬催化反應的應用研究及機理探讨。本論文工作（由王超同學于2006年首先嘗試）建立了合成1,2,3,4-四取代環戊二烯的有效方法。由于該類環戊二烯的獨特取代模式，其作為配體與過渡金屬配合預期将有獨特作用。