[Pd(NHC)(μ-Cl)Cl]2: Versatile and Highly Reactive Complexes for Cross-Coupling Reactions that Avoid Formation of Inactive Pd(I) Off-Cycle Products

Tongliang Zhou, Siyue Ma, Fady Nahra, Alan M.C. Obled, Albert Poater, Luigi Cavallo, Catherine S.J. Cazin, Steven P. Nolan, Michal Szostak

Research output: Contribution to journalArticle

Abstract

The development of more reactive, general, easily accessible, and readily available Pd(II)–NHC precatalysts remains a key challenge in homogeneous catalysis. In this study, we establish air-stable NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, as the most reactive Pd(II)–NHC catalysts developed to date. Most crucially, compared with [Pd(NHC)(allyl)Cl] complexes, replacement of the allyl throw-away ligand with chloride allows for a more facile activation step, while effectively preventing the formation of off-cycle [Pd2(μ-allyl)(μ-Cl)(NHC)2] products. The utility is demonstrated via broad compatibility with amide cross-coupling, Suzuki cross-coupling, and the direct, late-stage functionalization of pharmaceuticals. Computational studies provide key insight into the NHC–Pd(II) chloro-dimer activation pathway. A facile synthesis of NHC–Pd(II) chloro-dimers in one-pot from NHC salts is reported. Considering the tremendous utility of Pd-catalyzed cross-coupling reactions and the overwhelming success of [Pd(NHC)(allyl)Cl] precatalysts, we believe that NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, should be considered as go-to precatalysts of choice in cross-coupling processes.

Original languageEnglish (US)
Article number101377
JournaliScience
Volume23
Issue number8
DOIs
StatePublished - Aug 21 2020

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Catalysis
  • Chemistry
  • Inorganic Chemistry
  • Organic Synthesis

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