<scp>Palladium‐Catalyzed</scp>
Decarboxylative Homodimerization of Propiolic Acids: Synthesis of 1,
<scp>3‐Enynes</scp>
作者:Eunkyeong Seo、Jonghoon Oh、Sunwoo Lee
DOI:10.1002/bkcs.12221
日期:2021.3
was obtained as a result of a decarboxylative homodimerization reaction when a variety aryl propiolicacids were reacted in the presence of Pd(TFA)2/i‐PrPPh2 and K2CO3. It was found that aryl propiolicacids bearing an electrondonating substituent provided the desired product; however, aryl propiolicacids an bearing electron‐withdrawing substituent did not give the desired product.
当各种芳基丙酸在Pd(TFA)2 / i-PrPPh2和K 2 CO 3存在下反应时,通过脱羧均二聚反应获得1,3-烯炔产物。发现带有电子给体取代基的芳基丙酸提供了所需的产物。但是,带有轴承吸电子取代基的芳基丙酸不能提供所需的产物。
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
Iron can catalyze head-to-head dimerization of terminal aryl alkynes to give the corresponding (E) selective conjugated enynes in high yields. A variety of substituted aryl acetylenes underwent smooth dimerization using catalytic FeCl3 and DMEDA in the presence of KOtBu.