Palladium-mediated N-arylation of heterocyclic diamines: Insights into the origin of an unusual chemoselectivity
Palladium-mediated N-arylation of heterocyclic diamines: Insights into the origin of an unusual chemoselectivity
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DOI：
10.1021/jo062301i
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发表时间：
2007-03-16
影响因子：
3.6
通讯作者：
Rouden, Jacques
中科院分区：
文献类型：
--
作者：
Cabello-Sanchez, Noemi;Jean, Ludovic;Rouden, Jacques
研究了钯介导的溴苯与各种杂环二胺反应的化学选择性。无论使用哪种配体，3-氨基吡咯烷都会经历仲胺官能团的芳基化（> 82％），而更灵活的3-氨基氮杂平在其主要官能团上发生芳基化（> 70％）。 3-氨基哌啶与溴苯的“伯胺芳基化与仲胺芳基化”之比从 90:10（BINAP，富电子且受阻联苯 L2 或 L3）到 Josiphos 型配体 L10 的 32:68。当使用 4-氨基哌啶时观察到相同的趋势（L2 为 82:18，L10 为 17:83）。这种选择性可以通过选择具有不同空间和电子性质的芳基卤化物伙伴来调节。从竞争性实验中推断出反应过程中二胺的两个氮的协同作用。最后，在室温下使用 3-氨基吡咯烷进行的 C-13 和 P-31 NMR 实验支持伯胺与金属的快速配位。事实上，我们对中间体 ArPdX(BINAP) 的一个磷烷基团被伯氨基异常置换而产生的钯络合物进行了表征。
The chemoselectivity of the palladium-mediated reaction of bromobenzene with various heterocyclic diamines was studied. Whatever the ligand used, 3-aminopyrrolidine underwent arylation of the secondary amine function (> 82%), whereas the more flexible 3-aminoazepinine was arylated on its primary function (> 70%). The ratio "arylation of primary amine versus arylation of secondary amine" of 3-aminopiperidine with bromobenzene varied from 90:10 (BINAP, electron-enriched and hindered biphenyls L2 or L3) to 32:68 with the Josiphos-type ligand L10. The same trend was observed when 4-aminopiperidine was used (82:18 with L2 and 17:83 with L10). This selectivity can be tuned by the choice of aryl halide partners having different steric and electronic properties. A cooperative effect of both nitrogens of diamines during the reaction was deduced from competitive experiments. Finally, C-13 and P-31 NMR experiments, carried out with 3-aminopyrrolidine at room temperature, support a fast coordination of the primary amine to the metal. Indeed, a palladium complex resulting from the unusual displacement of one phosphane group of the intermediate ArPdX(BINAP) by the primary amino group was characterized.