Hydrochloric Acid → 6-Bromopyridine-3-sulfonyl chloride

Participants

Reaction Steps

To a cooled (0° C.-5° C.) stirred solution of 5-amino-2-bromopyridine (1.5 g, 8.6 mmol) in 12 N hydrochloric acid (26.5 mL), was slowly added a solution of sodium nitrite (0.66 g, 7.76 mmol) in water (7 mL). In a separate flask, sulfur dioxide was bubbled through a stirred solution of copper(II) chloride dihydrate (0.63 g, 3.50 mmol) in glacial acetic acid at 0° C. for 30 minutes, and then the diazotized reaction mixture prepared above was added. The resulting mixture was slowly warmed to room temperature and stirred for 30 minutes, then was poured into ice water (100 mL), and extracted with ethyl acetate (50 mL×3). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to afford the crude 6-bromo-pyridine-3-sulfonyl chloride, which was immediately used in the next step.

Provenance & Evidence