General procedure for the synthesis of 9-bromo-[1,2,4]triazolo[1,5-c]quinazolin-5(6H)-one from (4-bromo-2-cyanophenyl)carbamic acid ethyl ester and formylhydrazine: to a solution of (4-bromo-2-cyanophenyl)carbamic acid ethyl ester (40.4 g, 150 mmol) in N-methyl pyrrolidone (NMP, 170 mL), was added formylhydrazine ( 10.0 g, 150 mmol). The reaction mixture was stirred at 160°C for 1.5 hours in a mild nitrogen atmosphere. Upon completion of the reaction, the mixture was cooled to below 100°C and water (340 mL) was slowly added. The resulting slurry was further cooled to 25°C and stirred continuously for 15 minutes. The precipitated solid was collected by filtration and washed sequentially with water and 2-propanol. Finally, the product was dried under vacuum to afford 9-bromo-[1,2,4]triazolo[1,5-c]quinazolin-5(6H)-one (32.4 g, 81% yield) as a light yellow solid. Mass spectrometry (MS) analysis result: m/e = 264.9/267.0 (M + H+).
![9-Bromo-6H-[1,2,4]triazolo[1,5-c]quinazolin-5-one](/CAS/GIF/882517-92-2.gif)