To a reaction flask containing diethyl 2-(6-chloro-5-methylpyridin-3-yl)malonate 156-3 (1.00 g, 4.00 mmol), 2-methyl-4-(tributylstannyl)pyridine (1.53 g, 4.00 mmol) and Pd(PPh3)4 (440 mg, 0.4 mmol) under argon was added DMF (20 mL). The mixture was stirred at 120° C. for 10 hours. After the mixture was cooled down to room temperature, 1N KF aqueous solution was added to it and stirred for 15 minutes. The mixture was diluted with ethyl acetate and the two layers were separated. The organic layer was further washed with water and brine, dried over Na2SO4, concentrated to dryness by rotary evaporation. The crude product was purified by silica gel flash chromatography, eluted with 5% methanol in dichloromethane to give diethyl 2-(2′,3-dimethyl-2,4′-bipyridin-5-yl)malonate 156-4 as colorless oil. MS m/z 343.1 (M+1)
