An Easy Access to Construct Some Fused 1,2,4‐Triazines with Ring Junction Nitrogen Systems and Their Biological Evaluation

The chemical reactivity of 4‐amino‐6‐benzyl‐3‐mercapto‐1,2,4‐triazine‐5(4H)‐one (1) towards various aliphatic or/and mono and bis aromatic carboxylic acid derivatives to give the corresponding fused heterocyclic systems, 1,3,4‐thiadiazoles 4, 5, 6, which incorporating 1,2,4‐triazine nucleus was achieved. Moreover, compound 1 was subjected to react either with halo acetic acids or bromo ester to afford the respective fused nitrogen ring junction systems, thiadiazole 2 and 3, or thiadiazine 7. However, the tetracyclic ring system 9 was furnished through condensation reaction of isatine with triazine 1. In addition, some of the new synthesized compounds were evaluated as an antioxidant and antitumor agents.