[CH2:1]([O:8][C:9]1[CH:18]=[C:17]2[C:12]([C:13](=O)[N:14]=[CH:15][NH:16]2)=[CH:11][C:10]=1[F:20])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.P(Cl)(Cl)([Cl:23])=O>>[CH2:1]([O:8][C:9]1[CH:18]=[C:17]2[C:12]([C:13]([Cl:23])=[N:14][CH:15]=[N:16]2)=[CH:11][C:10]=1[F:20])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=17-(Benzyloxy)-6-fluoroquinazolin-4(1H)-one (2.00 g, 7.41 mmol) was taken up in phosphorus oxychloride (20 ml) and the reaction heated at reflux for 90 minutes. The reaction was cooled, azeotroped with toluene (2×50 ml) and taken up in dichloromethane (5 ml) The organic phase was washed with saturated aqueous sodium hydrogen carbonate solution and then dried over magnesium sulphate. Solvent evaporation in vacuo followed by drying of the solid in vacuo yielded 7-(benzyloxy)-4-chloro-6-fluoroquinazoline (1.50 g, 71% yield) as a pale yellow solid:
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