Hydroarylation gold catalysis

Thanks to a recent renaissance in gold catalysis, new gold-mediated transformations are being discovered with ever-increasing frequency. Some of these discoveries have been attributed to the action of gold vinylidenes. Fiirstner and coworkers uncovered one such example while screening catalysts for intramolecular alkyne hydroarylation (Scheme 9.23) [46]. 

The intramolecular reaction between furans and alkynes often does not yield the expected hydroarylation products, but, instead, gives phenols 6.220 in an efficient and selective manner (Scheme 6.96). This reaction was probably the first surprising transformation from gold catalysis, indicating that gold could be more than just an electrophilic trigger. 

Scheme 7.67 Tandem hydroamination-hydroarylation-transfer hydrogenation reaction catalysed by gold catalysis and chiral phosphoric acid...

By combining an initial gold-catalyzed hydroaminative indole formation with repetitive hydroarylations, Hirano et al. [48] reported the gold-catalyzed direct construction of highly fused carbazoles by multiple cyclization. Scheme 4.28 shows one example of this chemistry, and the overall yield of this pentacyclization is excellent, highlighting the efficiency of gold catalysis. 

---