A mixture of 3-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (500 mg, 1.57 mmol), (trimethylsilyl)acetylene (0.222 mL, 1.57 mmol), Et3N (0.329 mL, 2.36 mmol), CuI (4.5 mg, 0.0236 mmol), Pd(PPh3)2Cl2 (55.1 mg, 0.0785 mmol) and PPh3 (10.3 mg, 0.0393 mmol) in THF (7.5 mL) was heated to 40° C. for 8 h under Ar. To the suspension was added (trimethylsilyl)acetylene (0.111 mL, 0.785 mmol). The suspension was heated to 40° C. for 14 h under Ar. To the suspension was added (trimethylsilyl)acetylene (0.0888 mL, 0.628 mmol). The suspension was heated to 40° C. for 96 h under Ar. The mixture was diluted with brine, extracted with EtOAc, dried over MgSO4, filtered, concentrated in vacuo and purified by column chromatography on silica gel (hexane/EtOAc=50/50 to 0/100) to yield the title compound (148 mg, 28% yield) as a brown solid: 1H NMR (DMSO-d6, 300 MHz): δ ppm 0.26 (9H, s), 6.64 (1H, d, J=7.9 Hz), 7.75-7.92 (2H, m), 8.00-8.15 (2H, m), 8.90 (1H, d, J=8.3 Hz).
