Aryl-copper(III)-acetylides as key intermediates in C<inf>sp2</inf>-C <inf>sp</inf> model couplings under mild conditions

Mireia Rovira, Marc Font, Ferran Acuña-Parés, Teodor Parella, Josep M. Luis, Julio Lloret-Fillol, Xavi Ribas

    Research output: Contribution to journalArticleResearchpeer-review

    18 Citations (Scopus)

    Abstract

    The mechanism of copper-mediated Sonogashira couplings (so-called Stephens-Castro and Miura couplings) is not well understood and lacks clear comprehension. In this work, the reactivity of a well-defined aryl-Cu III species (1 ClO 4) with p-R-phenylacetylenes (R=NO2, CF3, H) is reported and it is found that facile reductive elimination from a putative aryl-CuIII-acetylide species occurs at room temperature to afford the Caryl - Csp coupling species (IR), which in turn undergo an intramolecular reorganisation to afford final heterocyclic products containing 2H-isoindole (PNO2, PCF3, PHa) or 1,2-dihydroisoquinoline (PHb) substructures. Density Functional Theory (DFT) studies support the postulated reductive elimination pathway that leads to the formation of C sp2-Csp bonds and provide the clue to understand the divergent intramolecular reorganisation when p-H-phenylacetylene is used. Mechanistic insights and the very mild experimental conditions to effect C aryl-Csp coupling in these model systems provide important insights for developing milder copper-catalysed Caryl - C sp coupling reactions with standard substrates in the future. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Original languageEnglish
    Pages (from-to)10005-10010
    JournalChemistry - A European Journal
    Volume20
    Issue number32
    DOIs
    Publication statusPublished - 4 Aug 2014

    Keywords

    • copper(III)
    • density functional calculations
    • Pd-free Sonogashira
    • reaction mechanisms

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