6-Amino-3-chloropyridazine → 3-Amino-4-bromo-6-chloropyridazine

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Reaction Steps

To a 250 mL round-bottomed flask was added 6-chloropyridazin-3-amine (3.92 g, 30.3 mmol), sodium bicarbonate (5.08 g, 60.5 mmol) and ethanol (20 mL). To the resulting solution, bromine (1.559 mL, 30.3 mmol) was added dropwise. The resulting mixture was stirred at room temperature for 16 hours. The solution was filtered and then concentrated in vacuo. The residue was dissolved in water, and the product extracted with ethyl acetate (3 times). The organic layers were combined, dried over anhydrous sodium sulfate and concentrated in vacuo to give 1A (4.5 g, 71.3% yield). HPLC: Rt=1.25 min (Waters Sunfire C18 column (4.6×50 mm). 10-90% aqueous methanol containing 0.1% TFA, 4 min gradient, flow rate=4 mL/min, detection at 254 nm). MS (ES): m/z=207.88 [M+H]+.

Provenance & Evidence