Pyridazines. Part 34: Retro-ene-assisted palladium-catalyzed synthesis of 4,5-disubstituted-3(2H)-pyridazinones

The efficient one-pot bis-functionalization of the 4,5-positions of the 3-pyridazinone ring has been performed using Suzuki, Sonogashira and Stille cross-coupling reactions assisted by a retro-ene fragmentation. This route allows access in a shorter synthetic sequence to several pharmacologically useful 3(2H)-pyridazinones.