Sodium hydride → 3-cyclopentyl-2-(4,5-dichloro-6-oxo-6H-pyridazin-1-yl)-propionic acid methyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of 4,5-dichloropyridazin-3(2H)-one (25.5 g, 154 mmol) in tetrahydrofuran was treated with 60% sodium hydride (7.42 g, 185.5 mmol) at 0° C. The reaction was stirred at 0° C. for 10 min, and then stirred at 25° C. for 1 h. At this time, the reaction was treated with 2-bromo-3-cyclopentyl-propionic acid methyl ester (Intermediate 10, 54.5 g, 185.5 mmol), and was stirred for 2 d at 50° C. The reaction solution was partitioned between water and ethyl acetate. The aqueous phase was extracted with ethyl acetate. The combined organic layers were washed with a saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. Chromatography (1/15 ethyl acetate/petroleum ether) afforded 3-cyclopentyl-2-(4,5-dichloro-6-oxo-6H-pyridazin-1-yl)-propionic acid methyl ester (23 g, 46.8%).

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