The well-established oxidative addition -reductive elimination pathway is the most followed one in transition metal catalyzed cross coupling reactions. While readily occurring with a series of transition metals, it does not take place with gold(I) complexes which have shown some reluctance to undergo oxidative addition unless special sets of ligands on gold(I), reagents or reaction conditions are used. A new possibility to overcome this hurdle has been devised. Upon visible light irradiation, an iridium photocatalyst triggers via triplet sensitization the oxidative addition of an alkynyliodide onto a vinylgold(I) intermediate to deliver Csp 2 -Csp coupling products after reductive elimination. Mechanistic and modeling studies support that an energy transfer takes place and not a redox pathway. This novel mode of activation in gold homogenous catalysis was applied in several dual catalytic processes. Alkynylbenzofuran derivatives were obtained from o-alkynylphenols and iodoalkynes in the presence of catalytic gold(I) and iridium(III) complexes under blue LED irradiation.Over the last two decades, homogeneous gold catalysis has been extensively used to efficiently and selectively promote a variety of cyclization processes. [1][2][3] The typical casting involves bifunctional substrates bearing an unsaturation prompt to electrophilic activation and a judiciously positioned internal nucleophile. A protodemetalation of the organogold intermediates to afford hydrofunctionalized products generally terminates the catalytic cycles. 4 Pursuing the step economy principle and also aiming at higher level of molecular complexity, some in situ post-functionalization reactions of the organogold 5 intermediate have been devised such as electrophilic halogenation or cross-coupling reactions. Although palladium catalyzed cross coupling from an organogold(I) intermediate has been

Photosensitization of organogold intermediates is an emerging field in catalysis. In this context, an access to 2,3-disubstituted indoles from o-alkynyl aniline and iodoalkyne derivatives via a gold-catalyzed sequence under visible-light irradiation and in the absence of an exogenous photocatalyst was uncovered. A wide scope of the process is observed. Of note, 2-iodo-ynamides can be used as electrophiles in this cross-coupling reaction. The resulting N-alkynyl indoles lend themselves to post-functionalization affording valuable scaffolds, notably benzo[a]carbazoles. Mechanistic studies converge on the fact that a potassium sulfonyl amide generates emissive aggregates in the reaction medium. Static quenching of these aggregates by a vinylgold(I) intermediate yields to an excited state of the latter, which can react with an electrophile via oxidative addition and reductive elimination to forge the key C-C bond. This reactant-induced photoactivation of an organogold intermediate opens rich perspectives in the field of cross-coupling reactions.

A convenient and mild protocol for the gold-catalyzed intermolecular coupling of o-alkynylphenols with haloalkynes to give vinyl benzofurans is reported. In this work, the gold catalyst SIPrAuCl and the co-catalyst NaBARF would corporately promote the intramolecular cyclization of the o-alkynylphenol to benzofuran, and then a selective hydroarylation of benzofuran to haloalkyne was catalyzed by the same catalysts. Computational studies suggest that the hydroarylation process takes place via a concerted nucleophilic attack pathway of the benzofuran to the C2 carbon of the activated haloalkyne, and reveal the original driving force of this hydroarylation process.