Transmetallation Versus β‐Hydride Elimination: The Role of 1,4‐Benzoquinone in Chelation‐Controlled Arylation Reactions with Arylboronic Acids |
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| Authors: | Dr Christian Sköld Jonatan Kleimark Alejandro Trejos Dr Luke R Odell Dr Sten O Nilsson Lill Prof Per‐Ola Norrby Prof Mats Larhed |
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| Institution: | 1. Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, BMC, P.O. Box 574, SE‐751 23 Uppsala (Sweden), Fax: (+46)?18‐4714474;2. Department of Chemistry, University of Gothenburg, Kemig?rden 4, 8076, SE‐412 96 G?teborg (Sweden) |
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| Abstract: | The formation of an atypical, saturated, diarylated, Heck/Suzuki, domino product produced under oxidative Heck reaction conditions, employing arylboronic acids and a chelating vinyl ether, has been investigated by DFT calculations. The calculations highlight the crucial role of 1,4‐benzoquinone (BQ) in the reaction. In addition to its role as an oxidant of palladium, which is necessary to complete the catalytic cycle, this electron‐deficient alkene opens up a low‐energy reaction pathway from the post‐insertion σ‐alkyl complex. The association of BQ lowers the free‐energy barrier for transmetallation of the σ‐alkyl complex to create a pathway that is energetically lower than the oxidative Heck reaction pathway. Furthermore, the calculations showed that the reaction is made viable by BQ‐mediated reductive elimination and leads to the saturated diarylated product. |
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| Keywords: | arylation C?C coupling density functional calculations elimination palladium transmetallation |
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