已开发出一种用于将多种简单和杂环芳烃与芳基碘化物、溴化物和氯化物进行分子内直接芳基化的催化剂。这些反应以极好的收率发生并且具有高度选择性。对芳基碘化物底物的研究表明,由于碘化物在反应介质中的积累,会发生催化剂中毒。这可以通过添加银盐来克服,银盐也允许这些反应在较低温度下发生。该方法的效用通过咔唑天然产物的快速合成和通过直接芳基化产物的开环反应合成空间位阻四邻位取代的联芳基来说明。机理研究提供了对催化剂的深入了解 s 作用模式并显示在钯催化的简单芳烃的直接芳基化中存在动力学上显着的 CH 键裂解。从这些研究中获得的知识导致了以前无法获得的芳烃的新分子间芳基化反应的发展,为其他新的直接芳基化过程的发展打开了大门。
Mild and efficient palladium-catalyzed intramolecular direct arylation reactions
作者:Marc Lafrance、David Lapointe、Keith Fagnou
DOI:10.1016/j.tet.2008.01.057
日期:2008.6
been evaluated in the context of intramoleculardirect arylation reactions. Under the optimal conditions, arylation of simple arenes can be performed under very mild conditions, with heating to 50 °C. The role of the pivalic acid additive is rationalized by invoking a concerted palladation–deprotonation pathway where the pivalate is behaving as either an intramolecular base from the palladium metal or
Reductive coupling of polyfunctionalized organobismuth and organolead arylating reagents in the synthesis of benzopyran derivatives
作者:A. Yu. Fedorov、J. -P. Finet、O. G. Ganina、M. I. Naumov、A. S. Shavyrin
DOI:10.1007/s11172-006-0163-9
日期:2005.11
Benzopyran derivatives were synthesized in good yields by the reactions of tris[2-(chloromethyl)phenyl]bismuth diacetate and 2-(halomethyl)aryllead triacetates with phenols and naturally occurring 4-hydroxycoumarins in the presence of bases according to a three-step one-pot procedure.
Catalyst-free synthesis of diversely substituted 6H-benzo[c]chromenes and 6H-benzo[c]chromen-6-ones in aqueous media under MWI
作者:Yan He、Xinying Zhang、Liangyan Cui、Jianji Wang、Xuesen Fan
DOI:10.1039/c2gc36379h
日期:——
6H-benzo[c]chromenes and 6H-benzo[c]chromen-8-ols via cascade reactions of 2-(2-(allyloxy)phenyl)furan and 2-(2-(prop-2-ynyloxy)phenyl)furan, featured with intramolecular Diels–Alder reactions of furan with unactivated alkene/alkyne in aqueous media under MWI, was developed. In addition, an environmentally friendly oxidation of 6H-benzo[c]chromenes into the corresponding benzo[c]chromen-6-ones using aqueous
在本文中, 催化剂不同地取代的6的-free合成ħ -苯并[ c ^ ]色烯和6 ħ -苯并[ c ^ ]苯并吡喃-8-醇通过的级联反应2-(2-(烯丙氧基)苯基)呋喃 和 2-(2-(丙-2-炔氧基)苯基)呋喃,具有分子内Diels–Alder反应 呋喃 与未激活 烯烃/炔烃在MWI下的水性介质中进行了开发。另外,环保氧化作用还揭示了在没有任何活化剂/催化剂的情况下,使用H 2 O 2作为氧化剂,将6 H-苯并[ c ]色烯转化为相应的苯并[ c ]色烯-6 。
Adhesive Catalyst Immobilization of Palladium Nanoparticles on Cotton and Filter Paper: Applications to Reusable Catalysts for Sequential Catalytic Reactions
Palladiumnanoparticles dispersed in ammonium salts of hyperbranched polystyrenes are adhesivelyimmobilized on the surface of cotton or filter papers by simply heating with dicarboxylic acids or halide anions. The resulting Pd@cotton and Pd@filter paper behave as reusablecatalysts; in particular, Pd@filter paper is useful as catalyst for application to sequential cross‐coupling and hydrogenation
Aryl–aryl cross-coupling reactions without reagents or catalysts: photocyclization of <i>ortho</i>-iodoaryl ethers and related compounds <i>via</i> triplet aryl cation intermediates
作者:Wei Sun、Luke Wilding-Steele、Richard C. D. Brown、David C. Harrowven
DOI:10.1039/d3cc03271j
日期:——
Cyclisations of benzyl ortho-iodoaryl ethers to benzo[c]chromenes can be effected without reagents or catalysts by irradiation with UVC under flow. Reactions proceed via triplet aryl cation generation, 5-exo and 3-exo-cyclisations, and rearomatisation. They have wide scope, are easy to effect and extend to a myriad of related ring systems.
苄基邻碘芳基醚环化成苯并[ c ]色烯可以在没有试剂或催化剂的情况下通过在流动下用UVC照射来实现。反应通过三线态芳基阳离子生成、5-外型和3-外型环化以及重新芳构化进行。它们的范围很广,很容易实现并扩展到无数相关的环系统。