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.

Pyrimidine and thienopyrimidine derivatives have attracted a great deal of interest owing to their medicinal activities (1-4). Pyrimidine derivatives and heterocyclic annelated pyrimidines continue to attract great interest due to the wide variety of interesting biological activities observed for these compounds, such as anticancer (4), antiviral (5), antitumor (6), anti-inflammatory (7) and antimicrobial activities (8). Also, the rapid growth in the literature dealing with the synthesis and biological activity of the thienopyrimidine derivatives prompted us to synthesize new derivatives of fused pyrimidine, thienopyrimidine and thienopyridine derivatives. In our previous work (9, 10), we reported the behaviour of thienopyrimidine derivatives towards hydrazines, 1,3-diketones, a-haloketones and acids. As part of this work, here we report a new synthesis strategy for the preparation of functionalized thieno [2,3-d] 5-Methyl-6-phenyl-2-thioxothieno[2,3-d]pyrimidone derivative (2) reacted with hydrazonoyl chloride derivatives to afford triazolothienopyrimidones 4a-f. Also, acetone--1-(2-amino-5-isopropyl-thiophene-3-carbonitrile) (3) reacted with functional and bifunctional groups to yield the corresponding compounds 5-11. The new products showed anti-inflammatory, analgesic, and ulcerogenic activities comparable to that of indomethacin and acetylsalicylic acid, respectively.

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This review presents a systematic and comprehensive survey of the methods of preparation of benzofurans. These compounds are important intermediates for the synthesis of a variety of synthetically useful and novel heterocyclic systems.

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