Phosphorus oxychloride → 3-Chloro-6-(4-fluorophenyl)-1,2,4-triazine

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Reaction Steps

A mixture of 6-(4-fluorophenyl)-1,2,4-triazin-3(2H)-one (1.0 g, 5.23 mmol) and phosphoryl chloride (8.0 mL) in chloroform (5.0 mL) was heated under reflux conditions overnight. After cooling, the volatiles were removed under reduced pressure. The residue was dissolved in dichloromethane (60 mL) and was poured into ice with stirring. The mixture was neutralized with aqueous 2N potassium carbonate and filtered through a pad of Celite. The organic layer was separated and the aqueous layer was extracted with dichloromethane (3×20 mL). The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography to give the desired product. (600 mg, 54.6%) 1H-NMR (300 MHz, CDCl3): 8.88 (s, 1H), 8.06-8.12 (m, 2H), 7.06-7.14 (m, 2H). LCMS: (M+H)=210.1/212.1.

Provenance & Evidence