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

Temperature

0 °C

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).

1. stirringThe mixture was stirred at 0° C. for 1 h
2. temperatureThe mixture was then heated to 100° C. under N2, for 16 h
3. customreaction at this point
4. additionIce-chips (10 g) were added to the cooled solution
5. stirringthe mixture was stirred for 20 minutes
6. washwashed with saturated aqueous NaHCO3 (2×50 mL) and brine (2×50 mL) via extraction
7. dry with materialdried over MgSO4
8. concentrationconcentrated
9. customto give a brown oil
10. customPurification by column chromatography

ORD record

ord-b63959f4ca5e4894bab45cdd7dd8a707

Source dataset

uspto-grants-2007_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07223759B2