الفهرس 
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Abstract
In the present investigation 6 known starting compounds, 10 novel intermediate compounds and 43 novel final compounds of uracil derivatives were synthesized. Several new 5-substituted uracil derivatives were prepared with the aim to have potent antiviral activity.
Moreover, new fused uracil derivatives whether bicyclic such as lumazines, xanthines and pyrimidopyrimidines or tricyclic as pyridodipyrimidines were prepared hopping to possess antiviral activity. Accordingly, to obtain such nonnucleoside uracil derivatives, the following routes were adopted:
1- Condensation of N,N-dimethylurea (Ia) or N-methylurea (Ib) with ethyl cyanoacetate (II) in sodium ethoxide via heating the reactants under reflux for 6 h. afforded 6-amino-1,3-dimethyluracil (IIIa) or 6-amino-1-methyluracil (IIIb). The nitrosation of compound IIIa with sodium nitrite in acetic acid gave the 5-nitroso derivative (IV) which on reduction with ammonium sulfide afforded 5,6-diamino derivative (VII).
2- Moreover, the nitroso derivative IV was reduced using zinc dust and formic acid to afford 5-formylaminouracil derivative (V) which on hydrolysis with HCl gas in methanol gave 5,6-diaminouracil hydrochloride derivative (VI).
3- The condensation of 5,6-diaminouracil derivative (VII) or its hydrochloride salt VI with different aldehydes afforded Schiff’s bases VIIIa-j using simple method by stirring the reactants together in water at room temperature for 15 min.<