开发了一种由金和钯催化π-活化由炔醇合成呋喃衍生物的集成方法。该合成策略是最显著的特点适用于带环辛基的底物，其适用范围比之前报道的有很大扩展。在Sonogashira反应条件下，由相应底物可直接得到环辛基呋喃。 Pd在这些反应中起到2个重要作用：底物发生偶联反应的关键催化剂；通过π-活化促进炔醇中间体成环反应。该方法在一步合成3-碘呋喃反应中作用很突出，使通过偶联法进一步官能团化成为可能。我们还将AuBr3用于多米诺成环/C–H键活化反应和无环前体的成环反应。本文结果表明，在该类成环反应中金和钯催化剂相辅相成。
This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzedπ‐activation chemistry. Notably, this new method was found to be amenable to cyclooctyl‐containing substrates, which represents a significant extension to this methodology compared with our previous reports. Fur‐thermore, this newly developed method allowed for the direct construction of cyclooctyl furans from their synthetic precursors under Sonogashira conditions. Experimental results revealed that palladium played two major functions in these reactions, including (1) an essential catalyst in the cross‐coupling reaction of the substrates;and (2) facilitating the cyclization of the acetylenic alcohol intermediates through a typicalπ‐activation process. The scope of this chemistry was highlighted by the one‐pot synthesis of 3‐iodofuran, which provided an opportunity for further functionalization (via coupling methods). Finally, the AuBr3 protocol was also elaborated to domino cyclization/C–H activation reactions, as well as the cyclization of acyclic precursors. Taken together, the results of this study demonstrate that gold and palladium catalysts can be used to complement each other in cyclization reactions.
参考文献
| [1] | C. Praveen;P. Kiruthiga;P. T. Perumal.Gold(III) Bromide Catalyzed Furannulation of 2-Alkynylcycloalk-2-enols: An Expedient Route to Fused Furans[J].Synlett,200912(12):1990-1996. |
| [2] | C. Praveen;S. Jegatheesan;P. T. Perumal.Gold(III) Chloride Catalyzed Intermolecular Dimerization of 2-Ethynylanilines: Synthesis of Substituted Quinolines[J].Synlett,200917(17):2795-2800. |
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