有效地实现了布朗斯台德酸(p -TsOH·H 2 O)促进吡咯与N,N-二甲基氨基亚甲基戊二酸二腈的烷基化/环化级联反应,从而提供具有优异非对映选择性的官能化环戊[ b ]吡咯。环戊[ b ]吡咯的相应铵盐与甲基碘的脱氨基反应生成二氢环戊[ c ]吡咯。通过反应中间体,即2-烷基化吡咯的分离和转化,证实了级联反应途径。
Palladium-Catalyzed Indole, Pyrrole, and Furan Arylation by Aryl Chlorides
作者:Enrico T. Nadres、Anna Lazareva、Olafs Daugulis
DOI:10.1021/jo1018969
日期:2011.1.21
The palladium-catalyzed directarylation of indoles, pyrroles, and furans by aryl chlorides has been demonstrated. The method employs a palladium acetate catalyst, 2-(dicyclohexylphosphino)-biphenyl ligand, and an inorganic base. Electron-rich and electron-poor aryl chlorides as well as chloropyridine couplingpartners can be used, and arylated heterocycles are obtained in moderate to good yields.
Well-Defined Palladium N-Heterocyclic Carbene Complexes: Direct C–H Bond Arylation of Heteroarenes
作者:Anuj Kumar、Manoj Kumar、Akhilesh K. Verma
DOI:10.1021/acs.joc.0c02024
日期:2020.11.6
A series of palladium N-heterocycliccarbene (NHC) complexes of type trans-(NHC)PdCl2L} (L = C5H5N, 3-ClC5H4N, and PPh3) (3–5) have been developed as efficient precatalysts for direct C–H bond arylation of various heteroarenes. In particular, an in situ generated new NHC ligand derived from 1,3-di-(2,6-diethylphenyl)acenaphtho[1,2-d] imidazolium} chloride (2) is used for the stabilization of the
反式-(NHC)PdCl 2 L}(L = C 5 H 5 N,3-ClC 5 H 4 N和PPh 3)的一系列钯N-杂环卡宾(NHC)配合物(3 – 5)已经开发出作为各种杂芳烃直接C–H键芳基化的有效预催化剂。特别地,使用由1,3-二-(2,6-二乙基苯基)ac [1,2- d ]咪唑鎓}氯化物(2)衍生的原位生成的新NHC配体来稳定钯金属中心。在筛选出的钯预催化剂中(3 – 5),最活跃的PEPPSI主题复合物(3)已成功用于各种杂芳烃和芳基溴化物的直接C–H键芳基化。在整个标准反应条件下,芳基溴化物和杂芳烃上的一系列官能团均可轻松获得各种芳基化杂环化合物。重要的是,该协议的实用性通过有效合成雷洛昔芬(一种选择性雌激素受体调节剂)的前体来证明。
Visible‐Light‐Induced N‐Heterocyclic Carbene‐Catalyzed Single Electron Reduction of Mono‐Fluoroarenes
An N-heterocyclic carbene (NHC)/tBuOK system was reported for the photoreduction of mono-fluoroarenes. Mechanistic studies suggest the generation of NHC radical anion as a potent reductant, and the Ar−F bond cleavage proceeds via a concerted mechanism, where single electron transfer, Ar−F bond cleavage and KF bond formation take place simultaneously.
据报道,N-杂环卡宾 (NHC)/ t BuOK 系统可用于单氟芳烃的光还原。机理研究表明,NHC 自由基阴离子的产生是一种有效的还原剂,Ar-F 键断裂通过协同机制进行,其中单电子转移、Ar-F 键断裂和 KF 键形成同时发生。