A mixture of 3-bromo-N-butylimidazo[1,2-b]pyridazin-6-amine (300 mg, 1.1 mmol), 3-fluoro-4-formylphenylboronic acid (230 mg, 1.3 mmol), dichloro-bis(triphenylphosphino) palladium (II) (40 mg, 0.055 mmol), potassium carbonate (230 mg, 1.7 mmol), acetonitrile (1.5 mL) and H2O (0.5 mL) was heated in a sealed conical vessel at 160° C. for 1000 s by microwave irradiation. The organic layer was separated and the aqueous layer was extracted with ethyl acetate (2 mL). The combined organic layers were concentrated under reduced pressure to afford an oil that was purified by reverse phase HPLC to afford 4-(6-butylamino-imidazo[1,2-b]pyridazin-3-yl)-2-fluorobenzaldehyde (240 mg, 68%) as a yellow solid: 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 10.39 (s, 1H), 8.28 (dd, J=12.9, 1.5 Hz, 1H), 7.91-8.01 (m, 3H), 7.73 (d, J=9.6 Hz, 1H), 6.54 (d, J=9.6 Hz, 1H), 3.48 (td, J=7.2, 5.8 Hz, 2H), 1.69-1.80 (m, 2H), 1.46-1.57 (m, 2H), 1.03 (t, J=7.5 Hz, 3H); LCMS (ESI) m/e 313.2 [(M+H)+, calcd for C17H18FN4O 313.1].
