Caesium fluoride (219 mg, 1.44 mmol) was added to a solution of 6-chloro-3′-fluoro-4-iodobiphenyl-3-ol (Preparation 99, 251 mg, 0.72 mmol) and 4-(tributylstannyl)pyridazine (345 mg, 0.93 mmol) in acetonitrile (5 mL). The reaction mixture was degassed and copper iodide (28 mg, 0.15 mmol) and tetrakistriphenylphosphinepalladium (0) (83 mg, 0.07 mmol) were added. The reaction mixture was stirred at 80° C. for 3 hours. The cooled reaction mixture was diluted with ethyl acetate (20 mL) and quenched with a solution of ammonia (10%, 10 mL) and stirred for a further 10 minutes. The organic layer was separated and washed with brine (1×10 mL), dried over MgSO4, filtered and concentrated in vacuo. The residue was purified using silica gel chromatography (Biotage) eluting with heptane:ethyl acetate (93:7 to 0:100) to give the title compound (185 mg, 62%) as a yellow solid.
