Gold complexes rearrangement

In contrast, this complex does not undergo homoleptic rearrangement in solution. It was the first diorganocarbene gold complex synthesized [68],... 

TABLE 12.8. Cationic Gold Complexes are Crucial for the Rearrangement... 

Alkenes act as nucleophiles with alkynes in the presence of gold catalysts. In the most simple version of the reaction, enynes are converted with gold complexes or salts, and in the absence of nucleophiles, into rearranged dienes, cyclopropanated carbocycles, and/or bicyclic cyclobutenes. Depending on the length of the tether and the nature of the substituents, the olefin attack to the alkyne occurs in an endo or an exo fashion (equation 33). Besides, substitution at the alkene plays an important role on the regioselectivity of the nucleophilic attack. ... 

The syntheses and catalytic applications of NHC - gold complexes have been reviewed. Details are given for their applications in enyne chemistry and carboxylic rearrangements, 7r-activation, and hydration reactions. Carboxylation catalysed by highly basic NHC-AuOH and NHC-CuOBu-t complexes has been highlighted. ... 

The gold(III)-catalysed rearrangement of tetrasubstituted 1-alkynyloxiranes shows that the gold complexes act as oxophilic Lewis acids rather than r-acids (Scheme 132). ... 

Perhalogenoaryls are more stable than the unsubstituted phenyls [176] and can be synthesized conveniently by oxidation of gold(I) complexes (demonstrating the stability of the Au-C bond). The initial product of oxidation addition seems to be the frans-isomer, which generally rearranges to the m-form ... 

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