Influence of a Very Bulky N-Heterocyclic Carbene in Gold-Mediated Catalysis

Adrian Gomez-Suarez, Ruben S. Ramon, Olivier Songis, Alexandra M. Z. Slawin, Catherine S. J. Cazin, Steven P. Nolan

Research output: Contribution to journalArticlepeer-review

98 Citations (Scopus)

Abstract

The syntheses of the free carbene IPr* (IPr* = 1,3-bis (2,6-b is (diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene) and related gold complexes [Au(IPr*)Cl] (C1) and [Au(IPr*)(NTf2)] (C2) were achieved in high yields. The % V-Bur of IPr* for both gold complexes was measured, revealing IPr* as one of the bulkiest NHCs on gold complexes reported to date. In addition, the catalytic activity of C1 and C2 in several reactions, typically catalyzed by Au-I complexes, was investigated. Examples include the tandem alkoxylation/lactonization of gamma-hydroxy-alpha,beta-acetylenic esters, the [3,3]-rearrangement of propargylic acetates leading to the formation of conjugated enones and substituted indenes, and the rearrangement of allylic acetates. These studies revealed a strong solvent effect on the catalytic activity with 1,2-dichloroethane as the solvent of choice. The screening of Cl and C2 demonstrated only slightly diminished activities in comparison to [Au(NHC)(L)] complexes bearing bulky ligands such as IPr and SIPr.

Original languageEnglish
Pages (from-to)5463-5470
Number of pages8
JournalOrganometallics
Volume30
Issue number20
Early online date22 Sept 2011
DOIs
Publication statusPublished - 24 Oct 2011

Keywords

  • EFFICIENT FORMATION
  • COMPLEXES
  • REARRANGEMENT
  • ACETATES
  • LIGAND
  • REACTIVITY
  • CONVERSION
  • NITRILES
  • ALCOHOLS
  • ESTERS

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