124-38-9

5922-60-1

1640-60-4

Under argon protection, 2-amino-5-chlorobenzonitrile (1 mmol) was dissolved in DMSO-d6 (1 mL), catalyst (0.01 mmol) was added and placed in a stainless steel autoclave. The autoclave was sealed, heated to 110 °C, and then carbon dioxide was introduced to reach a pressure of 2 MPa. The reaction mixture was subjected to cyclization by magnetic stirring at 110 °C for 3 h. After the reaction was completed, the autoclave was placed in the autoclave and the catalyst was added to the reaction mixture. Upon completion of the reaction, the autoclave was cooled in an ice bath and the pressure was slowly released. The chemical yield of 6-chloroquinazoline-2,4-dione was determined by 1H NMR analysis using 3,5-dimethoxybenzyl alcohol as an internal standard. Following the same procedure, a DMSO solution (6 mL) of 2-amino-5-chlorobenzonitrile (6 mmol) was subjected to a carboxycyclization reaction with carbon dioxide. After the reaction, the autoclave was cooled and depressurized and the reaction mixture was poured into water (60 mL). The precipitate was collected by filtration, washed sequentially with water and ether, and finally dried under vacuum at 35 °C for 15 h to give pure 6-chloroquinazoline-2,4-dione.