TY - JOUR
T1 - Competitive gold-activation modes in terminal alkynes
T2 - An experimental and mechanistic study
AU - Gimeno, Ana
AU - Cuenca, Ana B.
AU - Suárez-Pantiga, Samuel
AU - De Arellano, Carmen Ramírez
AU - Medio-Simõn, Mercedes
AU - Asensio, Gregorio
PY - 2014/1/13
Y1 - 2014/1/13
N2 - 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.
AB - 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.
KW - acetylides
KW - alkynes
KW - dual activation
KW - gold intermediates
KW - ligand effects
UR - http://www.scopus.com/inward/record.url?scp=84892365922&partnerID=8YFLogxK
U2 - 10.1002/chem.201304087
DO - 10.1002/chem.201304087
M3 - Article
AN - SCOPUS:84892365922
SN - 0947-6539
VL - 20
SP - 683
EP - 688
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 3
ER -