Modified (NHC)Pd(allyl)Cl (NHC = N-heterocyclic carbene) complexes for room-temperature Suzuki-Miyaura and Buchwald-Hartwig reactions

N Marion, O Navarro, JG Mei, ED Stevens, NM Scott, Steven Patrick Nolan

Research output: Contribution to journalArticlepeer-review

778 Citations (Scopus)

Abstract

A series of (NHC)Pd(R-allyl)CI complexes [NHC: IPr = N,N'-bis(2,6-diisopropylphenyl)imidazol2-ylidene, SIPr = N,N'-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene; R = H, Me, gem-Me-2, Ph] have been synthesized and fully characterized. When compared to (NHC)Pd(allyl)CI, substitution at the terminal position of the allyl scaffold favors a more facile activation step. This translates into higher catalytic activity in the Suzuki-Miyaura and Buchwald-Hartwig reactions, allowing for the coupling of unactivated aryl chlorides at room temperature in minutes. In the Suzuki-Miyaura reaction, aryl triflates, bromides, and chlorides react with boronic acids using very low catalyst loading. In the N-aryl amination reaction, a wide range of substrates has been coupled efficiently; primary-, secondary-, alkyl-, or aryl-amines react in high yields with unactivated, neutral, and activated aryl chlorides and bromides. In both reactions, extremely hindered substrates such as tri-ortho-substituted biaryls and tetra-ortho-substituted diarylamines can be produced without loss of activity. Finally, the present catalytic system has proven to be efficient with as low as 10 parts-per-million (ppm) of precatalyst in the Buchwald-Hartwig reaction and 50 ppm in the Suzuki-Miyaura reaction.

Original languageEnglish
Pages (from-to)4101-4111
Number of pages11
JournalJournal of the American Chemical Society
Volume128
Issue number12
DOIs
Publication statusPublished - 29 Mar 2006

Keywords

  • CROSS-COUPLING REACTIONS
  • PALLADIUM-CATALYZED AMINATION
  • HINDERED ARYL CHLORIDES
  • HIGHLY-ACTIVE CATALYST
  • ARYLBORONIC ACIDS
  • C-N
  • NUCLEOPHILIC CARBENES
  • ELECTRON-TRANSFER
  • STABLE CARBENES
  • ENERGY-TRANSFER

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