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Reaction of 6-amino-2-thiouracil 1 with ethyl bromoacetate yielded ethyl 2-(7-amino-2,5-dioxo-3,5-dihydro-2H-thiazolo[3,2-a]pyrimidin-6-yl)acetate 2. Reaction of 2 with sodium ethoxide afforded the pyrrolothiazolopyrimidine derivative 3. Compound 2 reacted with hydrazine hydrate to give 7-aminothiazolopyrimidine-carbohydrazide 4. The latter compound 4 reacted with carbon disulphide to form 7-amino-6-(oxadiazolylmethyl) thiazolopyrimidine 5. Compound 5 was heated in methanol to yield 9-thioxotriazolopyrrolothiazolopyrimidine 6. Also, the reaction of 3 with aromatic aldehydes afforded the diarylmethylenepyrrolothiazolopyrimidine derivatives 7a-c. The latter compounds 7a-c underwent cyclocondensation with hydroxylamine to give diaryldioxazolopyrrolothiazolopyrimidine derivatives 8a-c. The new prepared compounds were subjected for antioxidant and antituomer studies, some of these compounds exhibited promising activity.

The ultimate position of substituted 2-aminothiophenes in the field of drug design and synthesis of pharmaceuticals comes from their advantageous properties. The thiophene ring is bioisosteric replacement for the phenyl group broadly present in active drugs; the thiophene core exists in many natural and synthetic pharmaceuticals (1, 2). In the present work, ethyl-2-aminothiophene-3-carboxylic was expressed as a synthone for many new condensed heterocyclic systems viz. thieno [2,3-d] 2-Amino-5-acetyl-4-methyl-thiophene-3-carboxylic acid ethyl ester (1) and 5-acetyl-2-amino-4-methylthiophene--3-carbohydrazide (2) were synthesized and used as starting materials for the synthesis of new series of 1-pyrimidin-4(3H)-one (10) and 5-methyl-6-acetyl-2--thioxo-2,3-dihydrothieno[2,3-d]pyrimidin-4(1H)-one (12) as potential antioxidant and antitumor agents. Pharmacological tests showed that compounds 6a, 6b, 8, 10 and 12 exhibited significant antitumor and antioxidant activity.

6-[(4-Methoxy/4,9-dimethoxy)-7-methylfurochromen-5-ylideneamino]-2-thioxo-2,3-dihydropyrimidin-4-ones 1a,b were prepared by reaction of 6-amino-2-thiouracil with visnagen or khellin, respectively. Reaction of 1a,b with methyl iodide afforded furochromenylideneaminomethylsulfanylpyrimidin-4-ones 2a,b. Compounds 2a,b were reacted with secondary aliphatic amines to give the corresponding furochromen-ylideneamino-2-substituted pyrimidin-4-ones 3a-d. Reaction of 3a-d with phosphorus oxychloride yielded 6-chlorofurochromenylidenepyrimidinamines 4a-d, which were reacted with secondary amines to afford furochromenylideneamino-2,6-disubstituted pyrimidin-4-ones 5a-d. In addition, reaction of 5a-d with 3-chloropentane-2,4-dione gave 3-chloro-furochromenylpyrimidopyrimidines 6a-d. The latter were reacted with piperazine and morpholine to give 1-(furochromenyl)-pyrimidopyrimidine-3,6,8-triylpiperazines or-3,6,8-triylmorpholines 7a-d. The chemical structures of the newly synthesized compound ware characterized by IR, 1H-NMR, 13C-NMR and mass spectral analysis. These compounds were also screened for their analgesic and anti-inflammatory activities. Some of them, particularly 3-7, exhibited promising activities.

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