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

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Reaction Steps

Bromoacetaldehyde diethylacetal (13.7 g, 69.5 mmol, 1.8 equiv) was added to hydrobromic acid (4.0 mL) and heated to reflux for 1.5 h. The reaction mixture was cooled to rt then poured into a reaction flask containing excess sodium bicarbonate in isopropanol. The solution was stirred for 3 min and then filtered. To the mother liquor was added 3-amino-6-chloropyridazine (5.0 g, 38.6 mmol, 1.0 equiv) and heated to reflux for 2 h. The reaction mixture was quenched with water and extracted with ethyl acetate. Purification using column chromatography gave 5.1 g of the brown solid, 86%: 1H NMR (400 MHz, CDCl3) δ 7.89 (s, 1H), 7.88 (d, J=9.3 Hz, 1H), 7.74 (s, 1H), 7.01 (d, J=9.3 Hz, 1H).

Provenance & Evidence