Ammonium Chloride → 4,5-dihydro-6-phenyl-4-(pyridin-4-yl)pyridazin-3(2H)-one

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Reaction Steps

To a 200 ml, three-necked, round-bottomed flask equipped with a magnetic stir bar, 150 ml pressure-equalizing addition funnel, reflux condenser and a glass stopper, was added 21 g (135 mole) of 4-bromopyridine and 70 of anhydrous THF. The system was oven-dried and flushed with argon before use, 135 ml (135 mmole) of THF solution of phenylmagnesium bromide (1M) was placed in the pressure-equalizing addition funnel. Then, the Grignard solution was added dropwise over a period of 10 minutes. After the addition, the reaction was stirred for 15 minutes for completion. The solution of Grignard reagent was then obtained. A solution of 4-pyridylmagnesium bromide obtained above was added to a hot suspension of 6-phenylpyridazinone compound 7.8 g (45 mmole) in dry toluene (50 ml). The mixture was refluxed for 8 h, left overnight at ambient temperature, then decomposed with a saturated solution of ammonium chloride. The organic layer was separated, and the aqueous layer was extracted with 100 ml of ethyl acetate. The solvent was removed and the residue was crystallized from ethanol. The crystals were collected by filtering and dried over a medium frit sintered glass funnel in vacuo to give 5.6 g of white crystals. Yield was 50%, confirmed by ESI-MS. ESI-MS: m/z 252.1 (M+H+).

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