Tandem Photoredox and Copper-Catalyzed Decarboxylative C(sp3)-N Coupling of Anilines and Imines Using an Organic Photocatalyst
Guido Barzanò, Runze Mao, Marion Garreau, Jerome Waser and Xile Hu*
*Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fedérale dé Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne 1015, Switzerland,
Email: xile.huepfl.ch
G. Barzanò, R. Mao, M. Garreau, J. Waser, X. Hu, Org. Lett., 2020, 22, 5412-5416.
DOI: 10.1021/acs.orglett.0c01769
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Abstract
A catalytic amount of CuCl was used in combination with 4CzIPN as organic photoredox catalyst to effect decarboxylative C(sp3)-N coupling. The reaction provides a variety of alkyl amines from readily available alkyl carboxylic acids. The coupling worked with both anilines and imines as nitrogen sources.
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4CzIPN
proposed mechanism
Details
The document discusses a study on the tandem photoredox and copper-catalyzed decarboxylative C(sp3)−N coupling of anilines and imines using an organic photocatalyst, 4CzIPN, in combination with a copper catalyst, CuCl. This method enables the efficient synthesis of alkyl amines from readily available alkyl carboxylic acids. The organic photocatalyst 4CzIPN, which is inexpensive and easy to synthesize, was found to be more effective than previously used precious metal-based photocatalysts like Ru and Ir. The optimized conditions for the reaction include 1 mol % of 4CzIPN, 20 mol % of CuCl, and 1 equivalent of triethylamine in acetonitrile under blue LED light. The method showed high functional group tolerance and worked well with various anilines and imines, although it was less effective with electron-poor anilines and tertiary alkyl carboxylic acids. The study also explored the reaction mechanism, suggesting that the excited state of 4CzIPN is reductively quenched by triethylamine, leading to the formation of alkyl radicals that couple with aniline or imine partners. This work demonstrates the potential of organic photoredox catalysts in broadening the scope and efficiency of C(sp3)−N coupling reactions.
Key Words
ID: J54-Y2020