1214328-42-3

1415898-80-4

1214328-42-3

5-Chloro-1-yloxy-pyridine-2-carboxylic acid (3.5 g, 20 mmol) was slowly added to phosphorus trioxide (CAS 7789-59-5, 30 g) at 80 °C and the reaction was kept stirring for 2 hours. Upon completion of the reaction, the reaction mixture was quenched by careful pouring into ice water (100 mL) and subsequently extracted with ethyl acetate (3 x 50 mL). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to remove the solvent. The resulting crude product was purified by column chromatography (silica gel 100 g, eluent 50% petroleum ether solution of ethyl acetate) to give 2-bromo-3-chloro-6-carboxypyridine (1.12 g, 23% yield) as a gray solid. Mass spectrometry (EI) analysis showed: m/e 236.0 [M+H]+.