Phthalazinone in Heterocyclic Synthesis: Synthesis of Some s-Triazole,s-Triazolothiadiazine,s-Triazolothiadiazine,and s-Triazolothiadiazole Derivatives as Pharmaceutical Interest

1(2H)-Oxophthalazine-2-acetic acid ethyl ester was allowed to react with various reagents under different conditions to yield compounds 2-(4-substituted-5-mercaptotriazol-3-yl) methyl]-1 (2H)-oxophthalzines 5 and 7 which acted as starting materials for the preparation of some new s-triazolo5,1-b]1,3]thiazine (8), s-triazolo3,4-b]1,3,4]thiadiazine 9,12,14,20, and s-triazolo3,4-b]1,3,4]thiadiazole 18,21 derivatives.