Facile synthesis of 6-aryl 5-N-substituted pyridazinones: microwave-assisted Suzuki-Miyaura cross coupling of 6-chloropyridazinones

A facile synthesis of 5-dialkylamino-6-aryl-(2H)-pyridazin-3-one from 5,6-dichloropyridazinone was carried out by using a palladium-catalyzed Suzuki-Miyaura cross coupling of 6-chloro-5-dialkylaminopyridazinone 1 with various arylboronic acids (3 equiv) as the key transformation. The Suzuki-Miyaura cross-coupling reaction proceeded smoothly under microwave irradiation at 135-140 degrees C for 30 min with 5 mol % of Pd catalyst in moderate to good isolated yields. The use of a CombiPhos Pd6 mixture catalyst system and a single Pd-SPhos catalyst system was evaluated.