具有联芳基键的结构多样的芳族化合物的阴离子-自由基偶联以合理的收率产生了七个稠合的多环杂环。关键步骤(K,甲苯,O 2)的产率取决于电子和空间因素。整个策略仅包括两个步骤,从未取代的咪唑并[1,2- a ]吡啶开始,目标化合物的总收率为4–34%。咪唑并[1,5- a ]吡啶的衍生物也适用相同的策略。已经发现了这种垂直扩展的咪唑并[1,2- a ]吡啶的新工艺,该工艺包括顺序的Diels-Alder反应,然后是逆Diels-Alder反应。π-扩展咪唑[1,2-首次对α ]吡啶进行了充分表征,表明荧光量子产率显着低于单连接化合物。
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。