Hydrofunctionalization of n-Bonds

The addition of H X bonds (X = C, N, O, F) across unsaturated C-C bonds has become a major field of research with gold catalysts, and the use of NHCs as supporting ligands has proven beneficial in many instances. 

In 2003, Herrmann reported the hydration of alkynes with a NHC-Au compound. This was the first catalytic application involving NHCs in gold 

The same catalytic system also performed well in the hydroalkoxylation of allenes where the C-O bond was formed at the least hindered terminal carbon of the allene. This report was later the subject of a DFT study by Maseras and Patton. Interestingly, it was found that the addition of the alcohol likely occurred, in fact, at the most hindered carbon and was followed by a second hydroalkoxylation of the allylic ether and subsequent elimination, the whole process accounting for the observed regioselectivity. This second addition could nevertheless be impeded through appropriate choice of reaction conditions (i.e. DMF as solvent at 0°C with 10 equivalents of the alcohol), leading to the formation of the most substituted ether. 

Hydroamination of 7i-bonds is one of the most straightforward methods for the construction of C N bonds and, as such, has attracted a lot of attention. NHC- Au catalysts, in line with results obtained in hydration and hydroalkoxylation reactions (vide supra), proved highly efficient in this field and the inter-and intramolecular hydroamination of various alkenes, allenes, and alkynes were reported with a number of NHC- Au complexes. Among these reports, Widenhoefer published an elegant bis-hydroamination of allenes, leading 

Even though less studied than the O- and A-nucleophiles, other important H-X bonds can participate in hydrofunctionalization catalyzed by gold. Hence, the intermolecular hydroarylation i.e. bond addition) of allenes 

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