Synthesis of 1,4-dihydroimidazo[5,1-c]-1,2,4-triazin-4-ones and imidazo[5,1-c]-1,2,4-triazoles

Azo compounds obtained by the coupling of 5-diazoimidazoles with diethyl esters of nitro-, chloro-, bromo-, and acetylaminomalonic acids under conditions of base catalysis are cyclized to give 1,4-dihydroimidazo5,1-c]-1,2,4-triazin-4-ones or imidazo5,1-c]-1,2,4-triazoles. The chloro, bromo, and nitro groups in the bicyclic products are readily replaced by action of nucleophiles. The imidazotriazinones are converted to chloroimidazotriazines by reaction with thionyl chloride or phosphorus oxychlorideUrals State Technical University-UPI, 620002 Yekaterinburg, Russia Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1544–1553, November, 1999.