Microwave-assisted, palladium-catalyzed carbonylative cyclization--rapid synthesis of 2-quinolones from unprotected 2-iodoanilines and terminal alkynes

Palladium-catalyzed cyclocarbonylalions of 2-iodoanilines wiih various terminal alkynes nave been carried out by the use of commercially available molybdenum hexacarbonyl as a convenient and solid carbon monoxide source. The reactions were conducted at 160°C for 30 min under microwave irradiation and in the presence of [Et.sub.3]N in THF, affording the corresponding 2-quinolone derivatives in good regioselectivities and yields. Key words: microwave, palladium, carbonylation, 2-iodoaniline, 2-quinolone. Faisant appel a des catalyseurs de palladium et de l'hexacarbonyle de molybdene disponible commercialement comrae source eommode et solide de monoxyde de carbone, on a effectue des cyclocarbonylalions de 2-iodoanilines avec divers alcynes en position terminale. Les reactions ont ete effectuees a 160°C, pendant 30 minutes, sous irradialions de micro-ondes et en presence de [Et.sub.3]N dans le THF et elles conduisent a la formation des 2-quinoleones correspondantes avec de bons rendemenis el de bonnes regioselecliviles. Mots-cles : micro-onde, palladium, carbonylation, 2-iodoaniline, 2-quinoleone.
Introduction Undoubtedly, the transition-metal-catalyzed carbonylation has become one of the most important carbonyl-formation reactions in organic synthesis. (1) Particularly, palladium-catalyzed cyclocarbonylation of unsaturated substrates provides a unique, concise, and efficient [...]