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Unified synthesis of mono/bis-arylated phenols via Rh(III)-catalyzed dehydrogenative coupling
2,6-Bis-arylated phenols are rarely reported and are synthetically challenging. Directed C–H functionalization reactions, using a directing group (DG), might provide a convenient solution to their synthesis. However, this strategy usually results in partial cleavage of the directing group, preventin...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Royal Society of Chemistry
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308286/ https://www.ncbi.nlm.nih.gov/pubmed/28451162 http://dx.doi.org/10.1039/c6sc03169b |
Sumario: | 2,6-Bis-arylated phenols are rarely reported and are synthetically challenging. Directed C–H functionalization reactions, using a directing group (DG), might provide a convenient solution to their synthesis. However, this strategy usually results in partial cleavage of the directing group, preventing further/second C–H activation cascades. Herein we report a general strategy that allows for the precise control of the oxidation pathways so that directing groups can be either preserved or cleaved. We found that N-phenoxyacetamides could undergo ortho-arylation reactions with or without an external oxidant, yielding products with different oxidation states, notably the rare bis-arylated phenols. Notably, a unique rhodacycle intermediate was isolated, characterized by X-ray crystallography, and confirmed to be an active catalyst. Switching between internal and external oxidation could be a general strategy in diverse directed C–H functionalization reactions to realize bis-functionalized products. |
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