The first Pd-catalyzed tandem cyclization of imidazo[1,2-a]pyridines with 2-chlorobenzaldehydes throughC–Harylation and acylation is presented for the efficient synthesis of novel 6H-benzo[b]imidazo[5,1,2-de]quinolizin-6-ones. The direct acylation reaction proceeded smoothly without the aid of directing groups and in the presence of air as a clean and free terminal oxidant.
提出了通过C–H芳基化和酰化反应,用2-氯苯甲醛将Pd催化的咪唑并[1,2- a ]吡啶串联环化反应,以有效合成新型6 H-苯并[ b ]咪唑并[5,1,2] -德〕喹6人。直接酰化反应在没有引导基团的帮助下并且在作为清洁和游离末端氧化剂的空气存在下顺利进行。
Phosphine-Free Palladium-Catalyzed Direct Arylation of Imidazo[1,2-a]pyridines with Aryl Bromides at Low Catalyst Loading
作者:Hai Yan Fu、Lu Chen、Henri Doucet
DOI:10.1021/jo300528b
日期:2012.5.4
Ligand-free Pd(OAc)2 was found to catalyze very efficiently the directarylation of imidazo[1,2-a]pyridines at C3 under very low catalyst concentration. The reaction can be performed employing as little as 0.1–0.01 mol % catalyst with electron-deficient and some electron-excessive aryl bromides.
Direct catalytic C–H arylation of imidazo[1,2-a]pyridine with aryl bromides using magnetically recyclable Pd–Fe3O4 nanoparticles
作者:Jaewoo Lee、Jooyoung Chung、Sang Moon Byun、B. Moon Kim、Chulbom Lee
DOI:10.1016/j.tet.2013.04.031
日期:2013.7
The direct C–H arylation of a heteroarene with aryl bromides has been achieved under the catalysis of magnetic nanoparticles. In the presence of bimetallic Pd–Fe3O4 heterodimer nanocrystals (1 mol % in palladium), the reaction of imidazo[1,2-a]pyridine with various aryl bromides gives the corresponding arylated products with exclusive C3-selectivity. The highly regioselective method is applicable to
在磁性纳米粒子的催化下,杂芳烃与芳基溴的直接C–H芳基化反应已经实现。在双金属Pd–Fe 3 O 4异质二聚体纳米晶体(在钯中为1 mol%)的存在下,咪唑并[1,2- a ]吡啶与各种芳基溴化物的反应提供了具有独占C3选择性的相应芳基化产物。高度区域选择性的方法适用于各种具有不同电子和空间特性的芳基溴化物。Pd–Fe 3 O 4纳米晶体可以通过简单的磁分离而回收,并且已经被回收了十次而没有失去催化活性。
Magnetically recoverable nickel-palladium alloy nanocatalysts for direct C–H arylation reactions
in terms of the isolated product yields. The C–H arylationreactions were studied over a broad substrate scope (35 examples from 36 substrates) and gave the related biaryl products in good to excellent yields. Besides a broad substrate scope, the late-stage C–H arylation of zolimidine, a gastroprotective drug, was realized under the optimized reaction conditions. Moreover, the CoFe2O4-rGO/Ni20Pd80 nanocatalysts
新型磁性可回收纳米催化剂包含负载在还原氧化石墨烯 (rGO) 上的镍钯 (NiPd) 合金纳米粒子 (NPs),用钴铁氧体 (CoFe 2 O 4 ) NPs修饰,用于咪唑并吡啶、咪唑、茚茚的直接 C-H 芳基化和呋喃与芳基卤化物。为了制备所提出的催化剂,首先用合成的 CoFe 2 O 4 NPs 对rGO 纳米片进行改性,然后将获得的 CoFe 2 O 4 -rGO 纳米复合材料用作合成各种成分的双金属 NiPd 合金 NPs 的载体材料。得到的CoFe 2 O 4-rGO/NiPd 纳米催化剂通过许多先进的分析技术进行表征,包括 TEM、STEM-EDS、XRD、XPS 和 ICP-MS。接下来,为了优化反应条件,最初测试了具有不同合金成分的CoFe 2 O 4 -rGO/NiPd 纳米催化剂及其单金属对应物(CoFe 2 O 4 -rGO/Ni 和 CoFe 2 O 4 -rGO/Pd)咪唑并吡啶与溴苯的