La cyclisation intramoleculaire de composes diyniques a ete effectuee en utilisant l'une des combinaisons de reactifs: Cp 2 TiCl 2 /PMePh 2 /Na(Hg) ou Cp 2 ZrCl 2 /Mg/HgCl 2
Nickelocene as an Air- and Moisture-Tolerant Precatalyst in the Regioselective Synthesis of Multisubstituted Pyridines
作者:Il Young Cho、Woo Gyum Kim、Ji Hwan Jeon、Jeong Woo Lee、Jeong Kon Seo、Jongcheol Seo、Sung You Hong
DOI:10.1021/acs.joc.1c00577
日期:2021.7.16
Ni(COD)2-catalyzed cycloaddition reactions to access pyridines have been extensively studied. However, this catalyst typically requires drying procedures and inert-atmosphere techniques for the reactions. Herein, we report operationally simple nickel(0) catalysis to accesssubstituted pyridines from various nitriles and 1,6-diynes without the aid of air-free techniques. The Ni-Xantphos-based catalytic
Highly Stereo- and Regioselective Hydrocarboxylation of Diynes with Carbon Dioxide
作者:Tao Cao、Shengming Ma
DOI:10.1021/acs.orglett.6b00028
日期:2016.4.1
A nickel-catalyzed three-component hydrocarboxylation of diynes with ZnEt2 and CO2 (1 atm) is disclosed. With this method, symmetric/nonsymmetric diynes could be reacted smoothly with very high stereo- and regioselectivity, affording conjugated 2,4-alkadienoic acids incorporated with five- or six-membered rings efficiently. A stepwise non-oxidative cyclometalation mechanism was proposed based on careful
A Serendipitous Discovery: Nickel Catalyst for the Cycloaddition of Diynes with Unactivated Nitriles
作者:Puneet Kumar、Simon Prescher、Janis Louie
DOI:10.1002/anie.201104475
日期:2011.11.4
9‐dimethylxanthene (Xantphos) was used to access pyridines (see scheme). The reaction proceeds under ambient conditions to provide excellent yields of the products. Comparison of this catalyst with the other state‐of‐the‐art catalysts is also provided.
Cyclobutanones underwent a formal [4 + 2 + 2] annulation reaction with 1,6- and 1,7-diynes in the presence of nickel(0) catalysts to provide bicyclic eight-membered ring ketones. The annulation reaction proceeds through a ring-expansion of oxanickelacycloheptadiene via beta-carbon elimination to form a nine-membered nickelacycle. This reaction employing cyclobutanones as a C4 unit constructs cyclooctadienone
An Expeditious Route to Eight‐Membered Heterocycles By Nickel‐Catalyzed Cycloaddition: Low‐Temperature CC Bond Cleavage
作者:Puneet Kumar、Kainan Zhang、Janis Louie
DOI:10.1002/anie.201203521
日期:2012.8.20
diynes undergo a cycloaddition reaction catalyzed by Ni/IPr to give dihydroazocine compounds (see scheme; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolidene). The reaction involves a challenging CC bond cleavage step, yet, surprisingly, proceeds at low temperature.