20872-93-9

19815-17-9

General procedure for the synthesis of 4-chloro-7-nitroquinazoline from 7-nitroquinazolin-4(3H)-one: 7-nitroquinazolin-4(3H)-one (20.93 mmol) was suspended in 35 mL of thionyl chloride with catalytic amount of DMF (3 drops). The reaction mixture was refluxed at 110 °C for about 3 h until the solution became clear. Upon completion of the reaction, the excess thionyl chloride was removed by distillation under reduced pressure. Subsequently, anhydrous benzene was added to the residue and distilled again under reduced pressure to completely remove the residual thionyl chloride. The crude product obtained was dissolved in dichloromethane (CH2Cl2) and the pH was carefully adjusted to 7-8 with sodium carbonate (Na2CO3) solution.The reaction mixture was extracted with dichloromethane (CH2Cl2) and the organic phase was dried with anhydrous sodium sulfate (Na2SO4). Finally, the solvent was removed by concentration under reduced pressure to give the target product 4-chloro-7-nitroquinazoline (3.5 g, 16.74 mmol).