Premium
Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions
Author(s) -
Martinez Erin E.,
Jensen Christopher A.,
Larson Alexandra J. S.,
Kenney Karissa C.,
Clark Kyle J.,
Nazari S. Hadi,
ValdiviaBerroeta Gabriel A.,
Smith Stacey J.,
Ess Daniel H.,
Michaelis David J.
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202000483
Subject(s) - chemistry , sonogashira coupling , reactivity (psychology) , catalysis , steric effects , medicinal chemistry , coupling reaction , combinatorial chemistry , electronic effect , palladium , stereochemistry , polymer chemistry , organic chemistry , medicine , alternative medicine , pathology
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.