Amination reactions of aryl halides with nitrogen-containing reagents mediated by palladium/imidazolium salt systems

G A Grasa, M S Viciu, J K Huang, Steven Patrick Nolan

Research output: Contribution to journalReview articlepeer-review

357 Citations (Scopus)

Abstract

Nucleophilic N-heterocyclic carbenes have been conveniently used as catalyst modifiers in amination reactions involving aryl chlorides, aryl bromides, and aryl iodides with various nitrogen-containing: substrates. The scope of a coupling process using a Pd(0) or Pd(II) source and an imidazolium Salt in the presence of a base, (KOBu)-Bu-t or NaOH, was tested using various substrates. The Pd-2(dba)(3)/IPr . HCl (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) system presents the highest activity with respect to electron-neutral and electron-rich aryl chlorides. The ligand is also effective for the synthesis of benzophenone imines, which can be easily converted to the corresponding primary amines by acid hydrolysis. Less reactive indoles were converted to N-aryl-substituted indoles using as supporting ligand the more donating SIPr . HCl (5, SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). The Pd(OAc)(2)/SIPr . HCl/NaOH system is efficient for the N-arylation of diverse indoles with aryl bromides. The general protocol developed has been applied successfully to the synthesis of a key intermediate in the synthesis of an important new antibiotic. Mechanistically, palladium-to-ligand ratio studies strongly support an active species bearing one nucleophilic carbene ligand.

Original languageEnglish
Pages (from-to)7729-7737
Number of pages9
JournalThe Journal of Organic Chemistry
Volume66
Issue number23
DOIs
Publication statusPublished - 16 Nov 2001

Keywords

  • PALLADIUM-CATALYZED AMINATION
  • CROSS-COUPLING REACTIONS
  • ROOM-TEMPERATURE AMINATION
  • N-HETEROCYCLIC CARBENES
  • HIGHLY-ACTIVE CATALYST
  • ARYLBORONIC ACIDS
  • NUCLEOPHILIC-CARBENE
  • OLEFIN METATHESIS
  • BOND FORMATION
  • HECK REACTION

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