Hydrazine hydrate (1:1) → 6-[4-(3-chloropropoxy)-3,5-difluorophenyl]-2H-pyridazin-3-one

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Reaction Conditions

Reaction Steps

A mixture of 1-(4-(3-chloropropoxy)-3,5-difluoro-phenyl]ethanone (11 g, 44.7 mmol) and glyoxalic acid monohydrate (4.2 g, 46.5 mmol) in acetic acid (16 mL) was stirred at 100° C. for 4 h. The acetic acid was evaporated at reduced pressure and diluted with water then cooled to 0° C. and neutralized with ammonium hydroxide to pH 8. To this mixture, hydrazine monohydrate (4.3 mL, 86 mmol) was added and heated at 100° C. for 1 h. The reaction was cooled to rt and the solid was filtered, then dried to give a crude product. The crude product was triturated sequentially with 5% aqueous sodium bicarbonate solution and with a mixture of methylene chloride, methanol, ether and hexane to provide relatively pure product. The product was purified by ISCO (120 g silica gel column) chromatography using 2 to 8% methanol in methylene chloride to furnish 6-[4-(3-chloropropoxy)-3,5-difluorophenyl]-2H-pyridazin-3-one (7.9 g, 59%), MS m/z 301 (M+H).

Provenance & Evidence