Hydrogen Bromide → Imidazo(1,2-b)pyridazine, 6-chloro-

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Reaction Conditions

Reaction Steps

Hydrobromic acid (48% solution in water, 1.8 mL, 15.47 mmol) was added to a solution of 2-bromo-1,1-diethoxyethane (11.6 mL, 77.11 mmol) in water (18 mL) at ambient temperature and the resulting mixture was heated at 110° C. After 45 minutes, the reaction mixture was cooled and diethyl ether was added. The organic layer was separated, dried over magnesium sulphate and the solvent evaporated to obtain a colorless oil, which was added to a suspension at 0° C. of 6-chloropyridazin-3-amine (5.0 g, 38.60 mmol) in n-butanol (8 mL). The resulting mixture was heated at 130° C. overnight. The solvent was removed under reduced pressure, the residue was taken up in a mixture of ethyl acetate and water and the organic layer was separated. The aqueous layer was treated with solid sodium hydrogencarbonate until a basic pH was reached and extracted several times with ethyl acetate. The organic layers were combined, dried over magnesium sulphate and the solvent removed under reduced pressure. The resulting residue was treated with diisopropyl ether, filtered and dried in vacuo to yield the title compound (4.8 g, 85%) as a beige solid.

Provenance & Evidence