Synthesis of new nitrogen bases derived from the nucleic acid nitrogen base uracil in targeting the modification of the nucleic acid systems

2-Hydrazino derivative 3 was refluxed with aromatic aldehydes (1: 1, molar ratio) in presence of ethanol afforded Schiff's bases 4a-c. Reaction of 4-chlorobenzaldehyde with 2-hydrazino derivative 3 (1: 2, molar ratio) produced Schiff's base 6. On other hand, cyclization of compound 4b, using bromine (1: 1) in glacial acetic acid, the 5-bromo-open structure 7 was obtained. The cyclized structure 8 was formed on reacting 4b with bromine in (1: 2, molar ratio). 7-Amino-3-thioxo2,3-dihydro-1H, 5H-s-triazolo[4,3-a]primidin-5-one (12) was obtained upon treatment the potassium salt of derivative 3 with carbon disulphide. On stirring chloroacetyl chloride with 2-hydrazino derivative 3 in cold anhydrous dioxane, compound 8-amino-1,2,3,4-tetrahydro-6H-pyrimido[2,1-c]-as-triazine-3,6-dione (14) was produced. The reaction of 3 with either 2,4-pentanedione or 3-chloro-2,4-pentanedione furnish the class compound 16a,b. Heating under reflux compound 3 with ethyl acetoacetate furnish the cyclized product 17.