Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions. Issue 14 (21st June 2020)

• Record Type: Journal Article
• Authors: Martinez, Erin E.; Jensen, Christopher A.; Larson, Alexandra J. S.; Kenney, Karissa C.; Clark, Kyle J.; Nazari, S. Hadi; Valdivia‐Berroeta, Gabriel A.; Smith, Stacey J.; Ess, Daniel H.; Michaelis, David J.
• Is Part Of: Advanced synthesis & catalysis. Volume 362:Issue 14(2020)
• Page Start: 2876
• Page End: 2881
• Publication Date: 2020-06-21
• Subjects: carbenes -- catalysis -- cross-coupling -- palladium -- Suzuki-Miyaura; Catalysis -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Chemistry -- Periodicals; Chemistry, Technical -- Periodicals; Chemistry -- Periodicals; Catalysis -- Periodicals; Technology, Pharmaceutical -- Periodicals; 547.2
• DOI: 10.1002/adsc.202000483
• Languages: English
• ISSNs: 1615-4150

Abstract

Abstract: We report that treatment of several 2‐diphenylphosphinoimidazoles with Pd(II) salts generates monosubstituted N−H NHC−Pd complexes via insertion into the C−P bond. Removal of the N−H proton in situ leads to anionic (X‐type) or imidazolyl‐Pd complexes that are highly stable and catalytically active, achieving up to 340, 000 turnovers at 1 ppm catalyst loading in Suzuki‐Miyaura reactions. DFT‐calculated Tolman electronic parameters for the sterically small ligands suggest that these ligands are significantly more donating than traditional NHCs, which provides a rationale for rapid cross‐coupling catalysis. Excellent reactivity is also demonstrated in Sonogashira reactions. Abstract :