Competitive gold-activation modes in terminal alkynes: An experimental and mechanistic study

Ana Gimeno, Ana B. Cuenca, Samuel Suárez-Pantiga, Carmen Ramírez De Arellano, Mercedes Medio-Simõn, Gregorio Asensio

Research output: Indexed journal article Articlepeer-review

56 Citations (Scopus)

Abstract

The competition between π- and dual σ,π-gold-activation modes is revealed in the gold(I)-catalyzed heterocyclization of 1-(o-ethynylaryl)urea. A noticeable effect of various ligands in gold complexes on the choice of these activation modes is described. The cationic [Au(IPr)]+ (IPr=2,6-bis(diisopropylphenyl)imidazol-2-ylidene) complex cleanly promotes the π activation of terminal alkynes, whereas [Au(PtBu3)]+ favors intermediate σ,π species. In this experimental and mechanistic study, which includes kinetic and cross-over experiments, several σ-gold, σ,π-gold, and other gold polynuclear reaction intermediates have been isolated and identified by NMR spectroscopy, X-ray diffraction, or MALDI spectrometry. The ligand control in the simultaneous or alternative π- and σ,π-activation modes is also supported by deuterium-labeling experiments.

Original languageEnglish
Pages (from-to)683-688
Number of pages6
JournalChemistry - A European Journal
Volume20
Issue number3
DOIs
Publication statusPublished - 13 Jan 2014
Externally publishedYes

Keywords

  • acetylides
  • alkynes
  • dual activation
  • gold intermediates
  • ligand effects

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