Oxidative addition gold intermediates

Other alkylgold(III) compounds are [Au2(/r-X)2(CF3)4] (X = Br, I) synthesized by co-condensation of gold with CF3Br and CF3I, respectively, and may be sublimed at room temperature.1654 Trifluoromethylated compounds are potentially useful precursors for CVD studies as they are expected to show enhanced volatility.1655 m-[Au(CF3)2I(PMc3)] is formed in quantitative yield by oxidative addition of trifluoromethyl iodide to [Au(CF3)(PMe3)], the reaction is proposed to proceed via radical intermediates.1524,1656... 

Thallium(III) compounds usually react to cause oxidation of gold(I), but in certain cases arylgold(I) species have been isolated [Eqs. (11) and (12)] (38, 39). Oxidative addition was prevented in the former due to the inability of X to form the necessary bridges in the intermediate species (J[Pg.45]

Another possibility would be the use of allylic esters, which after a gold-catalyzed cycloisomerization with the carbonyl oxygen atom as the nucleophile deliver activated allylic intermediates which at the same time contain a vinylgold substructure. After transfer of an allyl cation to palladium(O), an oxidative addition to palladium, the vinylgold intermediate could transfer the organic moiety to palladium(II). A final reductive elimination would close the catalytic cycle. At the same time, no halide that potentially could deactivate the cationic gold(I) catalyst would be present. Indeed, Blum et al. [30] presented such systems. But... 

With the electTOTi-poor allenic esters, palladium(0) is able to catalyze the reaction without gold. The reactiOTi then is initiated at the other end, after oxidative addition of the aryl halide to the electrophilic palladium(II) species cycloisomerizes the allenic ester and then forms the product by reductive elimination. With o-alkynylbenzoates, the intermediate vinylgold species contains an enol ether substructure and is able to directly intercept the activated allyl donors, even in the absence of palladium. In both cases, by careful trace analysis (ICP), the presence of the other metal was excluded [78]. 

The majority of gold(I) carbene complexes are pure organometallic compounds and the are out of the scope of this work. Some halide or triphenylphosphine carbene complexes are known and they will be considered here. Nucleophilic addition of alcohols or amines to gold-coordinated isocyanides is one of the best-established methods to obtain gold carbene derivatives. The reaction of H[Au(CN)2] with propene oxide and estirene oxide yields (cyano)carbene complexes (380) avoiding the intermediate step.2257 A cyclic carbene compound is obtained by reaction of a dinuclear isocyanide with amine (Scheme 32).2258... 

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