Synthesis of N-Heterocycles by Reductive Cyclization of Nitro Compounds using Formate Esters as Carbon Monoxide Surrogates
Synthesis of N-Heterocycles by Reductive Cyclization of Nitro Compounds using Formate Esters as Carbon Monoxide Surrogates
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DOI：
10.1002/cctc.201701214
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发表时间：
2018-01-09
期刊：
影响因子：
4.5
通讯作者：
Ragaini, Fabio
中科院分区：
文献类型：
--
作者：
Formenti, Dario;Ferretti, Francesco;Ragaini, Fabio
在Pd和Pd/Ru催化的取代硝基化合物还原环化反应中，一系列烷基和芳基甲酸酯作为CO源被评价为杂环，特别是吲哚。甲酸苯酯被发现是最有效的，它允许以极好的产率获得所需的产品，通常高于以前报道的加压CO。通过详细的实验和动力学研究，我们能够区分金属催化和碱介导的甲酸苯酯的活化，并证实了只有碱才能有效地催化其脱羰反应。
A series of alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of substituted nitro compounds to afford heterocycles, especially indoles. Phenyl formate was found to be the most effective, and it allowed the desired products to be obtained in excellent yields, often higher than those previously reported with pressurized CO. Through detailed experiments and kinetic studies, we were able to discern between metal-catalyzed and base-mediated activation of phenyl formate and confirmed that just the base was effective in catalyzing its decarbonylation.