Phosphorus pentachloride → 5-Bromo-6-chloropyridine-3-sulfonyl chloride

Temperature

0 °C

A cooled (0° C.) solution of 6-amino-5-bromopyridine-3-sulfonic acid (12.65 g; 50.00 mmol) in HCl (60 ml; 5 N solution in water) was treated carefully with a solution of sodium nitrite (3.80 g; 55.0 mmol) in water (15 ml) and stirred at 0° C. for 1 hour. The solvents were evaporated and the residue was dried under high vacuum for 2 days, then treated with phosphorus pentachloride (15.00 g; 72 mmol) and phosphorus oxide chloride (0.50 ml; 5.5 mmol). The solid mixture was heated at 125° C. to give a refluxing solution. After heating at 75° C. for 3 hours, the solution was cooled and carefully poured on crushed ice. EtOAc was added and the phases separated. The organic phase was washed with brine, dried on MgSO4, filtered and concentrated under reduced pressure to give the title compound as a brown oil (14.91 g, quantitative yield), which was used without purification.

1. customThe solvents were evaporated
2. customthe residue was dried under high vacuum for 2 days
3. temperatureThe solid mixture was heated at 125° C.
4. customto give a refluxing solution
5. temperatureAfter heating at 75° C. for 3 hours
6. temperaturethe solution was cooled
7. additioncarefully poured
8. customon crushed ice
9. customthe phases separated
10. washThe organic phase was washed with brine
11. customdried on MgSO4
12. filtrationfiltered
13. concentrationconcentrated under reduced pressure

ORD record

ord-fae4a70d8b7942bb99751ee0b273f297

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08273769B2