Efficient and regioselective functionalization of imidazo[1,2-b]pyridazines via palladium-catalyzed cross-coupling reaction and SNAr

The synthesis of 3,6-disubstituted-2-phenylimidazo[1,2-b]pyridazine derivatives by palladium cross-coupling and SNAr reactions is described. Sonogashira and Stille cross-coupling reactions were investigated to introduce alkynyl, alkenyl, and aryl at the 3-position of imidazo[1,2-b]pyridazines. Then, at the 6-position, palladium-catalyzed N-arylation and direct SNAr were used to introduce amines and alcohols.