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Alkene-Chelated Ruthenium Alkylidenes: A Missing Link to New Catalysts
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-02-01 , DOI: 10.1021/acscatal.0c04972
Saswata Gupta 1 , Venkata R. Sabbasani 1 , Siyuan Su 1 , Donald J. Wink 1 , Daesung Lee 1
Affiliation  

A variety of heteroatom-chelated ruthenium alkylidenes have been developed as metathesis-active catalysts. Alkene-chelated ruthenium alkylidenes, however, have not been considered as a viable alternative because alkene coordination is a necessary step in the catalytic cycle. Relying on common design principles with varying steric and electronic factors, a series of structurally diverse alkene-chelated ruthenium alkylidene complexes were prepared by trapping the intermediates of enyne ring-closing metathesis (RCM) of 1,n-enynes and diynes with a stoichiometric amount of an initiator ruthenium complex. One of the crucial structural elements that promotes the formation of 1,5-alkene-chelates is the exo-Thorpe–Ingold effect, exerted by a gem-dialkyl moiety. These alkene-chelated complexes show a trans relationship between the N-heterocyclic carbene (NHC) ligand and the chelated alkene. On the other hand, η3-vinyl alkylidene complexes were generated from the RCM of ynamide-tethered 1,n-enynes. The presence of an ynamide moiety with a right connectivity is essential for the formation of these rare η3-vinyl alkylidene complexes with a cis relationship between the N-heterocyclic carbene (NHC) ligand and the chelated alkene. The stability and reactivity of these alkene-chelated ruthenium alkylidenes could be finely tuned to show characteristic behaviors in RCM, cross-metathesis (CM), and ring-opening metathesis polymerization (ROMP) reactions.

中文翻译:

烯烃螯合钌炔烃:与新催化剂的缺失环节

已开发出多种杂原子螯合的钌烷基亚烷基作为易位活性催化剂。然而,由于烯烃配位是催化循环中的必要步骤,因此烯烃螯合的钌烷基亚烷基未被认为是可行的选择。依靠具有不同空间和电子因素的通用设计原理,通过捕获化学计量的1,n-炔和二炔的烯环闭合复分解(RCM)中间体,制备了一系列结构多样的烯烃螯合的钌烷基亚烷基络合物。引发剂钌配合物的组成。促进1,5-烯烃-螯合物形成的关键结构要素之一是宝石产生的exo -Thorpe-Ingold效应-二烷基部分。这些烯烃螯合的配合物显示出N-杂环卡宾(NHC)配体与螯合的烯烃之间的反式关系。在另一方面,η 3从炔酰胺拴1的RCM产生-乙烯基亚烷基络合物Ñ -enynes。与右连接性的炔酰胺部分的存在为形成这些稀有η的基本3 -乙烯基亚烷基配合物与之间的顺式关系ñ -杂环卡宾(NHC)配体和螯合的烯烃。可以对这些烯烃螯合的钌烷基亚烷基的稳定性和反应性进行微调,以显示在RCM,交叉复分解(CM)和开环复分解聚合(ROMP)反应中的特征行为。
更新日期:2021-02-19
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