Iridium Catalyzed Synthesis of Tetrahydro-1H-Indoles by Dehydrogenative Condensation
Iridium Catalyzed Synthesis of Tetrahydro-1H-Indoles by Dehydrogenative Condensation
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DOI：
10.3390/inorganics7080097
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发表时间：
2019-08
期刊：
影响因子：
2.9
通讯作者：
Daniel Forberg;Fabian Kallmeier;R. Kempe
中科院分区：
文献类型：
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作者：
Daniel Forberg;Fabian Kallmeier;R. Kempe
常见的吲哚基序的新合成途径受到高度追捧。本文首次以仲醇和2氨基环己醇为原料，在铱催化剂的存在下合成了四氢- 1h -吲哚，采用了最近为合成氢咔唑而改进的合成方法。该催化剂由一种廉价且易于合成的三嗪基PN5P钳形配体稳定。该反应通过无受体脱氢缩合（ADC）进行，并产生标题化合物、二氢和水，因此可归类为可持续合成。总共制备了五个例子，其中三个是以前未知的化合物。良好的分离产率和温和的反应条件表明了该方法的合成价值。这些四氢吲哚可以在非均相钯催化剂上定量脱氢以产生相应的吲哚。
Novel synthetic routes to the commonly encountered indole motif are highly sought after. Tetrahydro-1H-indoles were synthesized for the first time from secondary alcohols and 2aminocyclohexanol in the presence of a well-established iridium catalyst using a modified synthetic procedure recently developed for the synthesis of hydrocarbazoles. The catalyst is stabilized by an inexpensive and easy-to-synthesize triazine based PN5P pincer ligand. The reaction proceeds through acceptorless dehydrogenative condensation (ADC) and yields the title compound, dihydrogen, and water and can thus be classified as sustainable synthesis. Overall, five examples, three of which were previously unknown compounds, were prepared. The propitious isolated yields and the mild reaction conditions show the synthetic value of this approach. These tetrahydroindoles can be quantitatively dehydrogenated over a heterogeneous Pd catalyst to yield the corresponding indoles.