Patricia Pérez-Galán

Gold(I)-Catalyzed Intermolecular Addition of Carbon Nucleophiles to 1,5- and 1,6-Enynes

Gold(I)-catalyzed addition of carbon nucleophiles to 1,6-enynes gives two different type of products by reaction at the cyclopropane or at the carbene carbons of the intermediate cyclopropyl gold carbenes. The 5-exo-dig cyclization is followed by most 1,6-enynes, although those bearing internal alkynes and alkenes react by the 6-endo-dig pathway. The cyclopropane versus carbene site-selectivity can be controlled in some cases by the ligand on the gold catalyst. In addition to electron-rich arenes and heteroarenes, allylsilanes and 1,3-dicarbonyl compounds can be used as the nucleophiles. In the reaction of 1,5-enynes with carbon nucleophiles, the 5-endo-dig pathway is preferred.

Metal–Arene Interactions in Dialkylbiarylphosphane Complexes of Copper, Silver, and Gold

Dialkylbiphenylphosphane-Au(I) complexes exhibit only weak metal-arene interactions with the covering arene ring. However, the contacts in isoleptic Ag(I) and Cu(I) complexes are shorter than the limiting values of 3.03 A (Ag(I)) and 2.83 A (Cu(I)). Strong metal-arene interactions were also found in the two Ag(I) aquo complexes and in two acetonitrile--Cu(I) complexes with dialkylbiphenylphosphane ligands. Arene-Ag(I) complexes with these bulky phosphane ligands show the strongest Ag(I)--arene bonds known.

Mechanism of the gold-catalyzed cyclopropanation of alkenes with 1,6-enynes

The gold(I)-catalyzed intermolecular cyclopropanation of alkenes with 1,6-enynes is an electrophilic process, which is mechanistically related to the well-known Simmons–Smith reaction proceeding through zinc carbenoids. This cyclopropanation is stereospecific, even in cases where the reaction was found to proceed stepwise.

Gold(I) Complexes with Hydrogen-Bond Supported Heterocyclic Carbenes as Active Catalysts in Reactions of 1,6-Enynes

Complexes [AuCl{C(NHR)(NHPy-2)}] (Py-2 ) 2-pyridyl; R ) Me, tBu, nBu, iPr, nheptyl) have been prepared in amodular way from [AuCl(CNPy-2)]. The carbene moiety has a hydrogen-bond supported heterocyclic structure similar to the nitrogen heterocyclic carbenes in the solid state, and in CH2Cl2 or acetone solution, which is open in the presence of MeOH. The compounds are good catalysts for the skeletal rearrangement of enynes, and for the methoxycyclization of enynes. In contrast, the complexes [AuCl{C(NHR)(NHPy-4)}] are scarcely active due to the blocking effect of the coordination position required for the catalysis by the nitrogen of the NHPy-4 group.

Carbocations or Cyclopropyl Gold Carbenes in Cyclizations of Enynes

Theoretical and experimental studies on the gold(I)-catalyzed formal [4+2] cycloaddition of dienynes are consistent with a mechanism that proceeds by means of cyclopropyl gold(I) carbenes instead of simple carbocations. This work shows that homoallylic stabilization is significant even for systems in which the tertiary carbocation is stabilized by two methyl groups.

A Cyclization–Rearrangement Cascade for the Synthesis of Structurally Complex Chiral Gold(I)–Aminocarbene Complexes

A facile synthesis of chiral cyclic alkyl aminocarbene-gold(I) complexes from gold-free 1,7-enyne substrates was developed. The novel cyclization-rearrangement reaction sequence is triggered by the addition of (Me2S)AuCl to different 1,7-enynes and leads to structurally unique carbene-gold(I) complexes in high yields. These novel complexes are catalytically active and inhibit the proliferation of different human cancer cell lines.