3-Imidazolyl-7-chloro-benzotriazine-1-oxide preparation

摘要

Preparation of 3-(imidazol-1-yl)-7-chlorobenzo-1,2,4-triazine-1-oxide of formula (I) involves (a) reacting 4-chloro-2-nitroaniline (II) with phosgene in the presence of toluene, (b) reacting the obtained 4-chloro-2-nitrophenyl isocyanate (III) with ammonia in the presence of toluene, (c) reacting the obtained 4-chloro-2-nitrophenylurea (IV) with aqueous sodium hydroxide in the presence of toluene, (d) reacting the obtained 3-hydroxy-7-chloro-benzo-1,2,4-triazine-1-oxide sodium salt (V) with a strong acid in the presence of toluene, (e) reacting the obtained 3-hydroxy-7-chloro-benzo-1,2,4-triazine-1-oxide (VI) with thionyl chloride in the presence of dibutyl formamide (DBF) and toluene, using 0.3-0.8 (preferably 0.4-0.7) mole DBF per mole (VI) and (f) reacting the obtained 3,7-dichloro-benzo-1,2,4-triazine-1-oxide (VII) with imidazole in the presence of sodium bicarbonate and toluene.