Pyrido[2,3-d]pyrimidine, 6-bromo-4-chloro-

155690-79-2

1215787-31-7

General procedure for the synthesis of 6-bromo-4-chloropyrido[2,3-d]pyrimidin-4(1H)-one from 6-bromopyrido[2,3-d]pyrimidin-4(1H)-one: 6-bromopyrido[2,3-d]pyrimidin-4(1H)-one (3.0 g) was mixed with phosphorus trichloride (POCl3, 15 mL) and heated to reflux for 3 hours at 130 °C under nitrogen atmosphere. Upon completion of the reaction, the dark homogeneous solution was concentrated under reduced pressure and diluted with ethyl acetate (EtOAc, 150 mL). The resulting brown non-homogeneous slurry was slowly poured into an ice-water mixture, neutralized to pH neutrality by the addition of sodium bicarbonate (NaHCO3), and the mixture was allowed to gradually warm to room temperature. Subsequently, the organic layer was separated by further diluting the mixture with ethyl acetate (75 mL). The organic layer was washed sequentially with saturated aqueous sodium chloride (NaCl), dried over anhydrous magnesium sulfate (MgSO4) and filtered through a diatomaceous earth pad and silica gel column. The filtrate was concentrated to give a light yellow crude product, which was recrystallized by stirring in a 50% ethyl acetate/hexane solvent mixture. After filtration, 6-bromo-4-chloropyrido[2,3-d]pyrimidine was obtained as a light yellow crystalline solid (1.8 g, purity: 95%).