Phosphorus oxychloride → 3-chloro-1-(4-fluorophenyl)pyrazin-2(1H)-one
Reaction equation
O=P(Cl)(Cl)[Cl:3].[F:6][C:7]1[CH:12]=[CH:11][C:10]([N:13]2[CH:18]=[CH:17][N:16]=[C:15](OC)[C:14]2=[O:21])=[CH:9][CH:8]=1>CN(C=O)C>[Cl:3][C:15]1[C:14](=[O:21])[N:13]([C:10]2[CH:11]=[CH:12][C:7]([F:6])=[CH:8][CH:9]=2)[CH:18]=[CH:17][N:16]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Conditions
- Temperature
- 0 °C
Procedure
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). 1H-NMR (400 MHz, CDCl3) δ 7.41 (m, 2H), 7.21 (m, 4H); 19F-NMR (376 MHz, CDCl3) δ −110.9.