ABSTRACT: Background: Recently, compounds such as pyrimidine, pyridazine, 1,2,4-triazepine, 1,3,4,6-oxatriazepine, pyridazino[1,2-a]pyrimidine, and pyridazino[1,2-c] pyrimidine, as well as their derivatives, have attracted attention due to their diverse biological activities. Objective: This study focuses on the synthesis of new heterocyclic compounds that feature a seven-membered ring, including pyridazinopyrimido[2,1-c] [1,2,4]triazepine-tetraones (4), pyridazinopyrimidotriazepine-triones (5-8), aminopyri-dazinopyrimido[2,1-c][1,2,4]triazepine-tetraone (9), and 6-amino-8-imino-pyridazino pyrimido[2,1-c] [1,2,4]triazepine-trione (10). These new compounds were synthesized starting from 1-(4-oxo-1,4-dihydropyrimidine)-1,2-di
