A mixture of 3-bromo-6-chloroimidazo[1,2-b]pyridazine (Preparation 1b, 182 mg, 0.78 mmol), 3-methoxy-4-(tributylstannyl)pyridazine (Preparation 8b, 313 mg, 0.78 mmol), copper(I) iodide (15 mg, 0.08 mmol) and dry N,N′-dimethylformamide (4 mL) in a Schlenk vial was subjected to three cycles of evacuation backfilling with argon. Tetrakis(triphenylphosphine)palladium(0) (91 mg, 0.08 mmol) was then added and the resulting mixture was subjected to three further cycles of evacuation backfilling with argon before being stirred at 100° C. for 20 hours. The reaction mixture was cooled down, the solvent was removed under reduced pressure and the residue was purified by flash chromatography (1:1 hexanes/ethyl acetate to 100% ethyl acetate) to give the title compound (131 mg, 64%) as a beige solid.
