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.
A Simple and Highly Efficient Iron Catalyst for a [2+2+2] Cycloaddition to Form Pyridines
作者:Chunxiang Wang、Xincheng Li、Fan Wu、Boshun Wan
DOI:10.1002/anie.201102001
日期:2011.7.25
Joined by iron: The ironcatalyst for the formation of pyridines at room temperature (see scheme), which was generated in situ from an inorganic iron salt and a diphosphine ligand, exhibited high reactivity and regioselectivity.
An in Situ Approach for Nickel-Catalyzed Cycloaddition
作者:Thomas N. Tekavec、Gang Zuo、Kristina Simon、Janis Louie
DOI:10.1021/jo0608669
日期:2006.7.1
pyridines from air-stable, commercially available catalyst precursors is described. The addition of n-BuLi to Ni(acac)2 and an NHC salt (such as IPr·HCl or SIPr·HCl) rapidly generates an active Ni(0)/NHC catalyst for the cycloaddition of diynes and nitriles that affords pyridines without a decrease in observed yields. The in situ method also converts diynes and carbon dioxide to the corresponding pyrones
作者:Michael M. McCormick、Hung A. Duong、Gang Zuo、Janis Louie
DOI:10.1021/ja0508931
日期:2005.4.1
A mild and general route for preparing pyridines from nitriles and diynes is described. Ni/imidazolyidene complexes were used to mediate cyclization alkynes and both aryl and alkyl nitriles at ambient temperature. In addition, the efficacy of this protocol allows for the preparation of a fused seven-membered pyridone and for intermolecular cyclizations. When an asymmetrical diyne was employed, cyclization
Eco-friendly synthesis of pyridines via rhodium-catalyzed cyclization of diynes with oximes
作者:Fen Xu、Chunxiang Wang、Haolong Wang、Xincheng Li、Boshun Wan
DOI:10.1039/c4gc01756k
日期:——
We describe a new route for the synthesis of pyridines via [2 + 2 + 2] cycloaddition of diynes and oximes catalyzed by Rh(NBD)2BF4/MeO-Biphep using ethanol as an alternative green reaction medium, affording the desired pyridine derivatives in yields of up to 93%. This environmentally friendly method meets the requirement for green chemistry by minimizing pollution from solvents and is tolerant of a