| abstract |
A compound of Formula III as the raw material is hydrolyzed in an alkaline condition, then acidized to prepare a compound of Formula IV, and the resulting compound of formula IV and a solid phosgene or diphosgene are concurrently subjected to the urea cyclization and the chloroformylation reaction in the presence of an organic base and a catalyst to obtain a compound of formula V, and then the compound of formula V is amidated to obtain the final product (II). In the present invention, a “one-pot” method is adopted for urea cyclization, chloroformylation, and amidation reaction, and the intermediate products do not need post-treatments such as separation and purification. |