The 4-quinazolinone analogue (8.0 mmol) was refluxed in a mixture of 27.4 mL sulfoxide containing N,N-dimethylformamide (2 drops) for 8 hours. After the reaction was complete, unreacted sulfoxide was removed under reduced pressure. The residue obtained by rotary evaporation was dissolved in dichloromethane. The solution was washed with saturated aqueous sodium bicarbonate solution and brine. The mixture was dried over anhydrous sodium sulfate. The mixture was concentrated under reduced pressure to give the product.
Synthetic route from phosphine oxychloride: 40.8 g of 6,7-bis(2-methoxyethoxy)quinazolin-4(3H)-one, 25.5 g (167 mmol), and triethylamine (33.7 g (334 mmol)) were added to a three-necked flask, followed by toluene. The resulting mixture was stirred at 70–80 °C for 3 hours. After the reaction was complete, excess POCl3 was removed by rotary evaporation.
Note that the material must not come into contact with water during post-processing, otherwise it may easily deteriorate.
