To a stirred solution of 2-benzyl-5-chloro-4-methoxypyridazin-3(2H)-one (20.0 g, 79.8 mmol) in toluene (500 mL) was added Pd(PPh3)4 (5.5 g, 4.76 mmol) under an atmosphere of argon. 4-Chlorophenylboronic acid (18.7 g, 119.6 mmol) was added subsequently. Under vigorous stirring, Na2CO3 (33.8 g, 318.9 mmol) pre-dissolved in water (90 mL) was added to the suspension. A stream of argon was bubbled through this suspension for 10 min. After this time, the flask was placed in an oil bath preheated at 120° C. The reaction was refluxed for 3 h. After this time, the reaction was cooled to RT The reaction mixture was then poured into water (200 mL). The layers were separated and the aqueous mixture was extracted with EtOAc (100 mL×3). The combined organic layers were washed with water (2×200 mL) followed by saturated aqueous NaCl (2×100 mL). The organic layer was then concentrated under reduced pressure to obtain crude product. This crude product was purified by silica gel column chromatography eluting with 8% EtOAc/hexanes to give the title compound, 2-benzyl-5-(4-chlorophenyl)-4-methoxypyridazin-3(2H)-one, (21.5 g, 82%) as a white solid. HPLC: 3.79 min; M+H=327. 1H NMR (CDCl3, 500 MHz): δ 7.76 (1H, s), 7.48 (2H, d, J=10.0 Hz), 7.40-7.45 (4H, m), 7.28-7.36 (3H, m), 5.35 (2H, s), 4.10 (3H, s).
