To a round bottom flask was added 2-benzyl-5-chloro-4-methoxypyridazin-3(2H)-one (25.1 gm, 0.1 mmol), 4-chlorophenyl boronic acid (17.215 gm, 0.11 mmol), Pd(PPh3)4(9.24 gm, 0.008 mmol), toluene (200 ml), EtOH (200 ml) and 2.0N Na2CO3 (200 ml, 0.4 mmol). The reaction was purged with argon for 10 min. The reaction was then heated to 120° C. and stirred at this temperature for 18 hrs. After this time, the reaction was cooled to rt, poured into a separatory funnel and the layers were separated. The aqueous layer was extracted with EtOAc (50 ml). The combined organic layers were washed with 1N NaOH (200 ml), water (200 ml) and saturated aqueous NaCl (200 ml). The organic layer was then slurried with MgSO4 to remove excess water, filtered and concentrated to give the crude product. The crude product was purified using an automated column chromatography system (ISCO, 330 gm silica gel) eluting with a gradient of 0-30% EtOAc/CH2Cl2 to give product 2-benzyl-5-(4-chlorophenyl)-4-methoxypyridazin-3(2H)-one (33 gm, 99% yield) as light yellow solid. HPLC retention time (method A) 3.740 min; LCMS (M+H)=327.2.
