Herein, we disclose the first C-2-selective C–H alkenylation of quinoline N-oxides catalyzed using a heterogeneous palladium catalyst. The protocol does not require the use of an external oxidant and it is applicable to an ample substrate scope always showing excellent site selectivity. This process is made accessible by the use of a specific 1,2,3-triazolium-tagged heterogeneous polymeric catalytic system. The catalyst can be efficiently recovered and reused with no decrease of its catalytic performance and hot filtration and mercury poisoning tests suggest that its mechanism of action is operatively heterogeneous. In addition, mechanistic studies revealed that C–H activation reaction pathways are operative, setting the stage for the direct synthesis of 2-functionalized quinolines using N-oxide functionality as both a directing group and an oxidant.

中文翻译：

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一种非均质且可回收的钯催化剂，可用于喹啉N-氧化物的区域选择性CH烯基化

在这里，我们公开了使用多相钯催化剂催化的喹啉N-氧化物的第一个C-2-选择性CH烯基化。该方案不需要使用外部氧化剂，并且适用于始终显示出色的位点选择性的充足的底物范围。通过使用特定的1,2,3-三唑鎓标记的异质聚合物催化系统，可以实现此过程。该催化剂可以有效地回收和再利用，而不会降低其催化性能，热过滤和汞中毒试验表明，其作用机理在操作上是异质的。此外，机理研究表明，C–H活化反应途径是可行的，为使用N直接合成2官能化喹啉奠定了基础。-氧化物官能团既是导向基团又是氧化剂。