Development of Versatile and Silver-Free Protocols for Gold(I) Catalysis

The use of a versatile N-heterocyclic carbene (NHC) gold(I) hydroxide precatalyst, [Au(OH)(IPr)], (IPr = N,N'-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene) permits the in situ generation of the [Au(IPr)](+) ion by simple addition of a Bronsted acid. This cationic entity is believed to be the active species in numerous catalytic reactions. H-1 NMR studies in several solvent media of the in situ generation of this [Au(IPr)](+) ion also reveal the formation of a dinuclear gold hydroxide intermediate [{Au(IPr)}(2)(mu-OH)], which is fully characterized and was tested in gold(I) catalysis.