Ethyl 2-chloroacetoacetate → Ethyl 6-chloro-2-methylimidazo[1,2-b]pyridazine-3-carboxylate

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Reaction Steps

A mixture of 6-chloropyridazin-3-amine (5.3 g, 41 mmol), ethyl 2-chloro-3-oxobutanoate (6.7 g, 41 mmol) and ethanol (50 mL) was heated under reflux for 2 days. The reaction mixture was concentrated under reduced pressure, saturated aqueous sodium bicarbonate solution and ethyl acetate were added to the obtained residue, and the insoluble material was filtered off. The filtrate was extracted with ethyl acetate, and the collected organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate. The insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. Ethyl acetate and diisopropyl ether were added to the obtained residue, and the insoluble material was filtered off. The obtained residue was purified by silica gel column chromatography (ethyl acetate/hexane=50/50→100/0) and washed with ethyl acetate/diisopropyl ether to give the title compound (3.2 g, 32%) as a colorless solid.

Provenance & Evidence