Phosphorus oxychloride → 2-Chloro-3,5-dibromopyridine

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Reaction Conditions

Reaction Steps

3,5-Dibromo-2-methoxy-pyridine (427) (1.5 g, 5.62 mmol) was dissolved in anhydrous DMF (14 mL) and chilled to 0° C. While stirring, POCl3 (2.1 mL, 22.48 mmol) was added drop wise over a period of 5 minutes. The mixture was stirred at 0° C. for 1 h. The mixture was then heated to 100° C. under N2, for 16 h. TLC indicated complete reaction at this point. Ice-chips (10 g) were added to the cooled solution and the mixture was stirred for 20 minutes. The mixture was diluted with EtOAc (200 mL), washed with saturated aqueous NaHCO3 (2×50 mL) and brine (2×50 mL) via extraction, dried over MgSO4 and concentrated to give a brown oil. Purification by column chromatography gave the desired product (428) as an off white solid upon concentration (1.01 g, 3.722 mmol, 66.2% yield). 1H NMR (400 MHz, CDCl3): δ 8.07 (d, 1H, J=2 Hz), 8.38 (d, 1H, J=1.6 Hz).

Provenance & Evidence