Gold complexes transition metal bonds

COMPLEXES WITH GOLD-TRANSITION METAL BONDS 904... 

Silver belongs to the late transition metals and, like gold, favors coordination to C=C triple bonds. A lot of silver-containing organometallic complexes, where silver-alkyne interactions assist the assembly of the complexes, are known. None of these complexes, however, was applied to efficient carbon-carbon bond formation in organic synthesis. 

Due to the lability of the Ag-Ccm-bene bond, silver NHC complexes of type 25 are useful agents for the NHC transfer reactions to transition metals. The preparation of silver NHC complexes using the Ag20 method and the transfer of the NHC ligand to other metal centers like gold has become a standard procedure in NHC complex synthesis. The Ag20 method often gives access to NHC complexes where alternative syntheses are tedious or not successful. 

Late transition metal-catalyzed processes also proved to be very useful tools for formation of the C-O bond of the 1,3-oxazine ring from the corresponding alkynes. In the presence of 1-5 mol% of a cationic gold(l) complex, A -BOC-protected alkynylamines 450 were converted to 6-alkylidene-l,3-oxazin-2-ones 451 under very mild conditions (Equation 49) <2006JOC5023>. 

Gold(I) isonitrile complexes were first reported (131) in 1956, when it was found that they were generally less stable than the isonitrile complexes of other transition metals. This was attributed to the low tendency of gold to form bonds with double bond character. A number of isonitrile complexes have been made, however, and they have been used extensively in the preparation of carbene and imino complexes of gold(I). 

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