Reactant-induced photoactivation of in situ generated organogold intermediates leading to alkynylated indoles via Csp2-Csp cross-coupling

Fen Zhao (1) , Mehdi Abdellaoui (1) , Wided Hagui (1) , Maria Ballarin-Marion (1) , Jérôme Berthet (2, 3) , Vincent Corcé (1) , Stéphanie Delbaere (2, 3) , Héloïse Dossmann (1) , Agathe Espagne (4) , Jérémy Forté (1) , Ludovic Jullien (4) , Thomas Le Saux (4) , Virginie Mouriès-Mansuy (1) , Cyril Ollivier (1) , Louis Fensterbank (1)

1 IPCM - Institut Parisien de Chimie Moléculaire
2 LilNCog - Lille Neurosciences & Cognition - U 1172
3 CHU Lille
4 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)

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 Nalkynyl 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 CC bond. This reactant-induced photoactivation of an organogold intermediate opens rich perspectives in the field of cross-coupling reactions.

Domaines: Chimie

Fen Zhao, Mehdi Abdellaoui, Wided Hagui, Maria Ballarin-Marion, Jérôme Berthet, et al.. Reactant-induced photoactivation of in situ generated organogold intermediates leading to alkynylated indoles via Csp2-Csp cross-coupling. Nature Communications, 2022, 13, pp.470. ⟨10.1038/s41467-022-29982-2⟩. ⟨hal-04009284⟩