Potassium Carbonate → 5-[(6-chloropyridin-3-yl)methyl]-2-(2,3-dimethylphenyl)-2,5-dihydro-3H-pyrazolo[4,3-c]pyrido[3,2-e]pyridazin-3-one

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Reaction Steps

Ethyl 1-[(6-chloropyridin-3-yl)methyl]-4-thioxo-1,4-dihydropyrido[2,3-c]pyridazine-3-carboxylate (389 mg, 1.08 mmol), (2,3-dimethylphenyl)hydrazine hydrochloride (279 mg, 1.62 mmol, 1.5 equiv) and potassium carbonate (1.49 g, 10.8 mmol, 10 equiv) were combined and placed into an oil bath preheated to 70° C. for 3 hours. The mixture was cooled to ambient temperature, poured into sodium bicarbonate (150 mL, aqueous saturated) and extracted with ethyl acetate (3×100 mL). The combined organic extracts were washed with brine (1×50 mL), dried with sodium sulfate, filtered and concentrated in vacuo. The residue was purified by silica gel gradient chromatography (100:0 to 0:100; hexanes:ethyl acetate containing 5% methanol), providing the titled compound as a deep red solid.

Provenance & Evidence