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 °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.