Ligand‐Controlled Diastereoselective Cobalt‐Catalysed Hydroalkynylation of Terminal Alkynes to
<i>E</i>
‐ or
<i>Z</i>
‐1,3‐Enynes
作者:Sebastian M. Weber、Jona Queder、Gerhard Hilt
DOI:10.1002/chem.202001697
日期:2020.9.21
A diastereoselectivehydroalkynylation of terminalalkynes to form the head‐to‐head dimerization products by two different cobalt‐phosphine catalyst system is reported. The use of the bidentate ligand dppp and additional triphenylphosphine led to the selective formation of the (E)‐1,3‐enynes (E:Z>99:1) in good to excellent yields, while the tridentate ligand TriPhos led to the corresponding (Z)‐1,3‐enynes
Alternative Reaction Pathways in Domino Reactions of Hydrazinediidozirconium Complexes with Alkynes
作者:Thorsten Gehrmann、Solveig A. Scholl、Julio Lloret Fillol、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/chem.201103497
日期:2012.3.26
Reaction of 1.2 equivalents of several diarylhydrazines and various substituted alkynes (1 equiv) at ambient temperature (or at 80 °C) in the presence of 10 mol % [Zr(NXyl)2Npy}(NMe2)2] (2 a) gave the corresponding indole derivatives. On the other hand, the replacement of 1,1‐diarylhydrazines by 1‐methyl‐1‐phenyl hydrazine led to head‐to‐head cis‐1,3‐enynes in good yields.
[Zr (NAr)2 N py }(NMe 2)2 ](Ar = 3,5-二甲苯基:2 a,异丁烯基:2 b)与一或两个摩尔当量的1,1-二苯肼反应生成混合物酰胺/肼基(1-)络合物[Zr (NMes)2 N py }(HNNPh 2)(NMe 2)](3),双肼基络合物[Zr (NMes)2 N py }(HNNPh 2)2 ](4),并且在存在过量的4-二甲基氨基吡啶(DMAP)的情况下,六配位肼基二氮杂锆配合物[Zr (NXyl)2 N py}(NN(Me)中PH)吡啶(DMAP)2 ](5)和[Zr的(NXyl)2 Ñ PY }(NNPh 2)吡啶(DMAP)2 ](6)。一个的等效锆- hydrazinediide [Zr的(NTBS)的反应2 Ñ PY }(NNPh 2)(吡啶)](1)在室温下具有二取代的炔烃16小时导致的7元diazazirconacycles形成7一–高产7
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