886365-47-5

1111638-41-5

886365-47-5

Procedure for the synthesis of 1-(5-bromo-2-chloropyridin-3-yl)ethanone (D-2-5): pyridine (13 g, 0.165 mol) was dissolved in dichloromethane (200 mL) at 0 °C, and chromium trioxide (CrO3, 8.25 g, 0.083 mol) and silica gel (20 mL) were added in batches with stirring. After addition, the reaction mixture was continued to be stirred for 10 minutes. Subsequently, 1-(5-bromo-2-chloropyridin-3-yl)ethanol (D-2-4, 6.5 g, 27.5 mmol) was added and the resulting mixture was stirred at room temperature overnight. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent: petroleum ether/ethyl acetate, 8:1) and it was confirmed that most of the raw material D-2-4 was converted. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to obtain the crude product D-2-5, which was further purified by column chromatography (silica gel, eluent: petroleum ether/ethyl acetate, 20:1) to obtain the pure D-2-5 (5 g, 77% yield) as a yellow oil.