Gold-Catalyzed Ascorbic Acid-Induced Arylative Carbocyclization of Alkynes with Aryldiazonium Tetrafluoroborates

We describe, herein, arylative carbocyclization of alkynes catalyzed by gold. In this process, Au­(I) is oxidized to Au­(III) with aryldiazonium tetrafluoroborates following a photosensitizer-free and irradiation-free protocol. Ascorbic acid acts as a radical initiator, generating aryl radicals. Acc...

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Bibliographic Details
Published in:ACS catalysis 2021-08, Vol.11 (15), p.8968-8977
Main Authors: Medina-Mercado, Ignacio, Colin-Molina, Abraham, Barquera-Lozada, José Enrique, Rodríguez-Molina, Braulio, Porcel, Susana
Format: Article
Language:English
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Summary:We describe, herein, arylative carbocyclization of alkynes catalyzed by gold. In this process, Au­(I) is oxidized to Au­(III) with aryldiazonium tetrafluoroborates following a photosensitizer-free and irradiation-free protocol. Ascorbic acid acts as a radical initiator, generating aryl radicals. According to DFT calculations, these radicals are added to Au­(I), leading to a Au­(II) species that is further oxidized to Au­(III) with the assistance of a tetrafluoroborate anion. The overall arylative carbocyclization process is very energetically favorable, transforming arylpropargyl ethers into valuable 3,4-diaryl-2H-chromenes in a completely regio- and stereoselective fashion. Furthermore, we show that one of the synthesized 3,4-diaryl-2H-chromenes exhibits polymorphism with marked differences in the color of its crystals, a property that could lead to the development of colored derivatives in the future.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.1c01826