Synthesis and reactions of 3‐thioxo[1,2,4]‐triazino[3,2‐ b ]quinazolin‐10‐ones

Thiation of [1,2,4]triazino[3,2‐ b ]quinazoline‐3,10‐dione 1 proceeds selectively to give the 3‐thioxo‐analog 3 . The latter was converted to the corresponding 3‐methylthio derivative 4 which was reacted with aniline and hydrazine to give the corresponding anilino‐ and hydrazino derivatives 5 and 7 . Compound 7 was converted to the hydrazones 8a,b and into the novel heterocyclic ring systems [1,2,4]triazolo[4′,3′:4,5][1,2,4]triazino‐[3,2‐ b ]quinazolin‐7‐ones 9, 10a,b and tetrazolo[1′,5′:4,5][1,2,4]triazino[3,2‐ b ]quinazolin‐7‐one 11 .