Visible‐Light‐Promoted Metal‐Free Synthesis of (Hetero)Aromatic Nitriles from C(sp 3 )−H Bonds**
| Autor: | Kathiravan Murugesan, Burkhard König, Karsten Donabauer |
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| Rok vydání: | 2020 |
| Předmět: |
ddc:540
photoredox catalysis Cyanation 010402 general chemistry 01 natural sciences Catalysis C−H functionalization chemistry.chemical_compound Molecule nitriles Ammoxidation Research Articles methylarenes 010405 organic chemistry Aryl Photoredox catalysis General Medicine C−H Functionalization | Hot Paper General Chemistry Nuclear magnetic resonance spectroscopy Combinatorial chemistry 0104 chemical sciences chemistry Catalytic cycle 540 Chemie ammoxidation Organic synthesis Photoredox catalysis• nitriles• C-H functionalization• methylarenes• ammoxidation Research Article |
| Zdroj: | Angewandte Chemie Angewandte Chemie (International Ed. in English) |
| ISSN: | 1521-3773 1433-7851 |
| DOI: | 10.1002/anie.202011815 |
| Popis: | The metal‐free activation of C(sp3)−H bonds to value‐added products is of paramount importance in organic synthesis. We report the use of the commercially available organic dye 2,4,6‐triphenylpyrylium tetrafluoroborate (TPP) for the conversion of methylarenes to the corresponding aryl nitriles via a photocatalytic process. Applying this methodology, a variety of cyanobenzenes have been synthesized in good to excellent yield under metal‐ and cyanide‐free conditions. We demonstrate the scope of the method with over 50 examples including late‐stage functionalization of drug molecules (celecoxib) and complex structures such as l‐menthol, amino acids, and cholesterol derivatives. Furthermore, the presented synthetic protocol is applicable for gram‐scale reactions. In addition to methylarenes, selected examples for the cyanation of aldehydes, alcohols and oximes are demonstrated as well. Detailed mechanistic investigations have been carried out using time‐resolved luminescence quenching studies, control experiments, and NMR spectroscopy as well as kinetic studies, all supporting the proposed catalytic cycle. C(sp3)−H bonds have been converted to cyano derivatives under metal‐ and cyanide‐free condition in the presence of visible light and an organic dye. Potential applications of this method in the late‐stage transformation of complex drug molecules, steroid derivatives, and gram‐scale reactions have been described. |
| Databáze: | OpenAIRE |
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