Stable, Yet Highly Reactive Nonclassical Iron(II) Polyhydride Pincer Complexes: <i>Z</i>-Selective Dimerization and Hydroboration of Terminal Alkynes
作者:Nikolaus Gorgas、Luis G. Alves、Berthold Stöger、Ana M. Martins、Luis F. Veiros、Karl Kirchner
DOI:10.1021/jacs.7b05051
日期:2017.6.21
polyhydride complexes containing tridentate PNP pincer-type ligands is described. These compounds of the general formula [Fe(PNP)(H)2(η2-H2)] exhibit remarkable reactivity toward terminalalkynes. They efficiently promote the catalytic dimerization of aryl acetylenes giving the corresponding conjugated 1,3-enynes in excellent yields with low catalyst loadings. When the reaction is carried out in the presence
描述了含有三齿 PNP 钳型配体的非经典铁 (II) 氢化物配合物的合成、表征和催化活性。这些通式[Fe(PNP)(H)2(η2-H2)]的化合物对末端炔表现出显着的反应性。它们有效地促进芳基乙炔的催化二聚化,以极低的催化剂负载量以优异的产率得到相应的共轭 1,3-烯炔。当反应在频哪醇硼烷存在下进行时,得到乙烯基硼酸酯。这两个反应都在温和的条件下进行,并且具有高度的化学选择性、区域选择性和立体选择性,Z 选择性高达 99%。
CuSO<sub>4</sub>-H-phosphonate catalyzed highly stereo- and regioselective dimerization of terminal alkynes
The readily available CuSO4-H-phosphonate catalytic system can catalyze the head-to-head dimerization of terminal alkynes to give the corresponding (E) conjugated enynes selectively in high yield.
in toluene at 145 °C for 2 h to give the corresponding head-to-head dimers in good to excellent yields (54 to 99%) with high E-selectivity (67 : 33 to 83 : 17 E/Z). Both strongly electron-donating and electron-withdrawing groups are compatible with this procedure. The bidentate phosphine (dppe) ligand exhibits better catalytic activity than the bidentate amine (DMEDA). The aliphatic acetylene fails to
在DMEDA或dppe的存在下,使用FeCl 3和KO t Bu实现了末端芳基炔烃的区域选择性二聚,以产生共轭烯炔。反应在145°C的甲苯中平稳进行2小时,以高至E的选择性(67:33至83:17 E / Z)以良好至优异的收率(54%至99%)得到相应的头对头二聚体)。强供电子基团和吸电子基团均与该程序相容。双齿膦(dppe)配体显示出比双齿胺(DMEDA)更好的催化活性。脂肪族乙炔无法在该催化体系下反应,这表明叔丁醇钾通过阳离子-π相互作用和pi-pi相互作用激活了芳基乙炔的共轭体系。自由基抑制剂(galvinoxyl或TEMPO)可完全抑制反应。使用FeCl 2代替FeCl 3作为催化剂,仅苯基乙炔以良好的收率提供了相应的头对头二聚体。FeCl 3催化芳基炔烃和FeCl 2的二聚反应的机理途径 已经提出了苯基乙炔的催化二聚作用。
A K-arylacetylide complex for catalytic terminal alkyne functionalization using KO<sup>t</sup>Bu as a precatalyst
作者:Jasimuddin Ahmed、Asim Kumar Swain、Arpan Das、R. Govindarajan、Mrinal Bhunia、Swadhin K. Mandal
DOI:10.1039/c9cc07833a
日期:——
Herein we report a transition metal free catalytic terminal alkyne functionalization across the C–X triple bond (X = CH and N) with E-selective homo (alkyne–alkyne) and head-to-tail selective hetero (alkyne–nitrile) dimerization. A series of stoichiometric reactions enabled us to crystallize a reactive organometallic intermediate K-arylacetylide complex which was characterized by X-ray crystallography
Novel Regio- and Stereoselective Dimerization of Terminal Alkynes Catalyzed by Rare-Earth Silylamide
作者:Kimihiro Komeyama、Ken Takaki、Katsuomi Takehira
DOI:10.1055/s-2004-822314
日期:——
exhibit good catalyst activities for regio- and stereoselective dimerization of terminal aliphatic and aromatic alkynes in the presence of amine additives. Thus, using tertiary amine additives. particularly N(SiMe 3 ) 3 , aliphatic terminalalkynes were efficiently converted to head-to-tail dimers. On the other hand, only Z-head-to-head dimers were obtained in high yields from aromatic alkynes with the