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
Organic Photoredox Catalysis for Pschorr Reaction: A Metal-Free and Mild Approach to 6H-Benzo[c]chromenes
作者:Gaofeng Feng、Jing-Yao He、Qi-Fan Bai、Chengan Jin
DOI:10.1055/s-0037-1610279
日期:2018.10
under mild conditions by using eosinY as a photoredox catalyst and acetonitrile as the solvent. The diazonium salts can be either preformed or generated in situ from the corresponding amines with t -BuONO. The process is amenable to gram-sale synthesis of 6 H -benzo[ c ]chromenes, which can be further transformed into both 6 H -benzo[ c ]chromen-6-ones through oxidation or to 6 H -benzo[ c ]chromen-6-amine
已开发出一种方便的有机光氧化还原 Pschorr 反应,为 6 H-苯并 [c] 色烯开辟了一条合成路线。该过程可以在温和的条件下通过使用曙红Y作为光氧化还原催化剂和乙腈作为溶剂进行。重氮盐可以由相应的胺与 t-BuONO 预先形成或原位生成。该工艺适用于6 H-苯并[ c ]色烯的克销售合成,其可以通过氧化进一步转化为6 H-苯并[ c ]色烯-6-酮或6 H-苯并[ c ]色烯-6-胺通过 sp 3 C-H 键胺化。该协议为合成 6 H-苯并 [c] 铬库提供了一条有吸引力的途径。
Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles
作者:Rafael Cano、Juana M. Pérez、Diego J. Ramón、Gerard P. McGlacken
DOI:10.1016/j.tet.2015.12.039
日期:2016.2
magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular