Cycloisomerization versus Hydration Reactions in Aqueous Media: A Au(III)-NHC Catalyst That Makes the Difference
作者:Eder Tomás-Mendivil、Patrick Y. Toullec、Josefina Díez、Salvador Conejero、Véronique Michelet、Victorio Cadierno
DOI:10.1021/ol300811e
日期:2012.5.18
A novel water-soluble Au(III)-NHC complex has been synthesized and successfully applied in the intramolecular cyclization of gamma-alkynoic acids into enol-lactones under biphasic toluene/water conditions, thus representing a rare example of an active and selective catalyst for this transformation In aqueous media. Remarkably, competing alkyne hydration processes were not observed, even during the desymmetrization reaction of challenging 1,6-diyne substrates. In addition, after phase separation, the water-soluble Au(III) catalyst could be recycled 10 times without loss of activity or selectivity.
Water-Soluble Gold(I) and Gold(III) Complexes with Sulfonated <i>N</i>-Heterocyclic Carbene Ligands: Synthesis, Characterization, and Application in the Catalytic Cycloisomerization of γ-Alkynoic Acids into Enol-Lactones
作者:Eder Tomás-Mendivil、Patrick Y. Toullec、Javier Borge、Salvador Conejero、Véronique Michelet、Victorio Cadierno
DOI:10.1021/cs4009144
日期:2013.12.6
2-pyridyl, 2-picolyl, and 2-pyridylethyl substituents have been synthesized and employed as precursors for the preparation of novel water-soluble Au(I)- and Au(III)-NHC complexes of general composition [AuCl(NHC)] and [AuCl3(NHC)] (NHC = N-heterocyclic carbene), respectively. These complexes proved to be active, selective, and recyclable catalysts for the intramolecular cyclization of γ-alkynoic acids under