Gold(I) Carbenoids: On-Demand Access to Gold(I) Carbenes in Solution.

Chloromethylgold(I) complexes of phosphine, phosphite, and N-heterocyclic carbene ligands are easily synthesized by reaction of trimethylsilyldiazomethane with the corresponding gold chloride precursors. Activation of these gold(I) carbenoids with a variety of chloride scavengers promotes reactivity typical of metallocarbenes in solution, namely homocoupling to ethylene, olefin cyclopropanation, and Buchner ring expansion of benzene.

α,β-Unsaturated Gold(I) Carbenes by Tandem Cyclization and 1,5-Alkoxy Migration of 1,6-Enynes: Mechanisms and Applications.

1,6-Enynes bearing OR groups at the propargyl position generate α,β-unsaturated gold(I)-carbenes/ gold(I) stabilized allyl cations that can be trapped by alkenes to form cyclopropanes or 1,3-diketones to give products of α-alkylation. The best migrating group is p-nitrophenyl ether, which leads to the corresponding products without racemization. Thus, an improved formal synthesis of (+)-schisanwilsonene A has been accomplished.

Modular chiral gold(i) phosphite complexes†Electronic supplementary information (ESI) available: Experimental results and NMR data. CCDC 933751 (), 933752 (), 933753 (), 933754 (), 933756 (), 933757 (). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3cy00250kClick here for additional data file.Click here for additional data file.

Chiral gold(i) phosphite complexes are readily prepared modularly from 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol. These chiral gold(i) phosphite complexes are very reactive precatalysts for the [4+2] cycloaddition of aryl-substituted 1,6-enynes with enantiomeric ratios ranging from 86 : 14 up to 94 : 6.

Selective formation of adjacent stereocenters by allylboration of ketones under mild neutral conditions.

Allylboronic acids readily react with a broad variety of ketones, affording homoallylic alcohols with adjacent quaternary and tertiary stereocenters. The reaction proceeds with very high anti stereoselectivity even if the substituents of the keto group have a similar size. α-Keto acids react with syn stereoselectivity probably due to the formation of acyl boronate intermediates.

Palladium-catalyzed synthesis and isolation of functionalized allylboronic acids: selective, direct allylboration of ketones.

Textbook revision: allylboronic acids, which are easily prepared from allylic alcohols, react readily and selectively with ketones without Lewis acid catalysts.

Phosphate ligands in the gold(I)-catalysed activation of enynes.

Gold(I) forms neutral complexes with binol phosphates that are unreactive in the catalytic cyclisation of enynes. Reaction in protic solvents or activation by silver(I) restores the catalytic activity.

Sulfoxide-alkene hybrids: a new class of chiral ligands for the Hayashi-Miyaura reaction.

Sulfoxide-alkene hybrids are introduced as a new class of chiral heterodentate ligands for the Hayashi-Miyaura reaction. The synthesis of these ligands was achieved without the use of protecting groups. A chiral resolution was performed via simple column-chromatographic separation of the diastereomeric ligands.

A multipurpose gold(I) precatalyst.

[Au(tmbn)(2)](SbF(6)) is the first gold(I) complex supported by two nitrile ligands that is indefinitely stable at room temperature. This is a highly versatile precatalyst that can be used for the preparation of active and robust solid-supported gold(I) catalysts.

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.

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.

Gold(I)-catalyzed cyclizations of 1,6-enynes: alkoxycyclizations and exo/endo skeletal rearrangements.

Gold(I) complexes are the most active catalysts for alkoxy- or hydroxycyclization and for skeletal rearrangement reactions of 1,6-enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletal rearrangement of enynes by the endocyclic cyclization pathway are also documented.