Phosphorus oxychloride → 3-chloro-1-(4-fluorophenyl)pyrazin-2(1H)-one

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Reaction Conditions

Reaction Steps

POCl3 (5.6 mL, 61.3 mmol) was added dropwise to a solution of 1-(4-fluorophenyl)-3-methoxypyrazin-2(1H)-one in DMF (30 mL) with stirring at 0° C. followed by heating at 90° C. for 1.5 hours. The residue was cooled to 0° C., quenched by adding saturated sodium acetate solution, extracted with CH2Cl2, washed with water, dried over MgSO4, and concentrated. The crude was purified by silica gel flash column chromatography (0.7% MeOH in CH2Cl2) to afford 3.52 g (64%) of the desired product. LRMS (ESI pos) m/e 224.9, 227.0 (M+1, Cl pattern).

Provenance & Evidence