Filters

2017 - 20202

More filters

2021 - 20232
Reset filters

Settings

Subject: Catalytic reactions × WGL Institute: LIKAT ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Origins of high catalyst loading in copper(i)-catalysed Ullmann-Goldberg C-N coupling reactions
    (Cambridge : RSC, 2017) Sherborne, Grant J.; Adomeit, Sven; Menzel, Robert; Rabeah, Jabor; Brückner, Angelika; Fielding, Mark R.; Willans, Charlotte E.; Nguyen, Bao N.
    A mechanistic investigation of Ullmann-Goldberg reactions using soluble and partially soluble bases led to the identification of various pathways for catalyst deactivation through (i) product inhibition with amine products, (ii) by-product inhibition with inorganic halide salts, and (iii) ligand exchange by soluble carboxylate bases. The reactions using partially soluble inorganic bases showed variable induction periods, which are responsible for the reproducibility issues in these reactions. Surprisingly, more finely milled Cs2CO3 resulted in a longer induction period due to the higher concentration of the deprotonated amine/amide, leading to suppressed catalytic activity. These results have significant implications on future ligand development for the Ullmann-Goldberg reaction and on the solid form of the inorganic base as an important variable with mechanistic ramifications in many catalytic reactions.
  • Thumbnail Image
    Item
    Aldehydes and ketones influence reactivity and selectivity in nickel-catalysed Suzuki-Miyaura reactions
    (Cambridge : RSC, 2020) Cooper, Alasdair K.; Leonard, David K.; Bajo, Sonia; Burton, Paul M.; Nelson, David J.
    The energetically-favorable coordination of aldehydes and ketones-but not esters or amides-to Ni0 during Suzuki-Miyaura reactions can lead either to exquisite selectivity and enhanced reactivity, or to inhibition of the reaction. Aryl halides where the C-X bond is connected to the same π-system as an aldehyde or ketone undergo unexpectedly rapid oxidative addition to [Ni(COD)(dppf)] (1), and are selectively cross-coupled during competition reactions. When aldehydes and ketones are present in the form of exogenous additives, the cross-coupling reaction is inhibited to an extent that depends on the strength of the coordination of the pendant carbonyl group to Ni0. This work advances our understanding of how common functional groups interact with Ni0 catalysts and how these interactions affect workhorse catalytic reactions in academia and industry. This journal is © The Royal Society of Chemistry.