The reaction of pyrazolobenzothienopyrimidine-3-carbaldehyde 1 with thiocarbohydrazide afforded the Schiff's base 3. The latter compound reacted with some electrophilic reagents to give 1,2,4-triazoles 4-6 and 1,2,4-triazines 7-9. Treatment of compound 3 with 2-cyano-3,3-bis(methylthio)acrylonitrile gave the corresponding 5-amino-4-cyano-3-methylthiopyrazole derivative 11. The reaction of pyrazole 11 with carbon disulfide afforded dithioxopyrazolopyrimidine 12. Acylation of compound 11 by using acetic anhydride yielded acetamide 13. On the other hand, the cyclocondensation of pyrazole 11 with acetic anhydride in pyridine yielded pyrazolopyrimidine derivative 14. The reactivity of compound 11 towards formamide and phenylisothiocyanate to give the pyrazolopyrimidines 15 and 16 was studied. The newly synthesized compounds were screened for their antimicrobial activity.

10-Oxo-4,6,7,8,9,10-hexahydroprazolo[1,5-a][1]benzothieno[2,3-d]pyrimidine-3-carbaldehyde (2) was prepared by Vilsmeier-Haack reaction of 3-amino-2-methyl-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one (1). Reaction of carbaldehyde derivative 2 with malononitrile afforded arylidene malononitrile 3. Cyclization of the latter compound with thiourea yielded pyrimidinethione 4. Interaction of carbaldehyde derivative 2 in presence of thiourea with keto- compounds such as ethyl acetoacetate, or acetylacetone, or dimedone or ethyl cyanoacetate gave pyrimidine derivatives 5-8. Hydrazinolysis of carbaldehyde derivative 2 gave the hydrazone 9. Reaction of the latter with phenyl isothiocyanate afforded thiosemicarbazone 10, which underwent cyclization with oxalyl chloride to give thioxoimidazolidinedione 11. Condensation of compound 2 with thiosemicarbazide furnished thiosemicarbazone derivative 12. Reaction of compound 2 with aminopyrazolone in the presence of an acid and/or a base afforded pyrazolones 13 and 14. Treatment of carbaldehyde derivative 2 with cyanoacetohydrazide gave acrylohydrazide 15. Interaction of the latter with carbon disulfide yielded mercaptooxadiazole 16.  Condensation of compound 2 with acetylpyridazinone 17 produced chalcone 18. Reaction of  compound 18 with malononitrile in pyridine gave cyanopyran 19, while its reaction with malononitrile in presence of ammonium acetate in ethanol yielded cyanopyridine 20. Structures of the newly synthesized products have been deduced on the basis of elemental analysis and spectral data. The synthesized compounds were screened for their antimicrobial activity.

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1-[4-(3-Hydroxyphenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl]eth anone (1) was used as a precursor for heterocyclic synthesis. Condensation of compound 1 with monochloroacetic acid and benzaldehyde gave thiazolopyrimidine 2 which in turn underwent cyclization with malononitrile dimmer to afford malononitrile derivative 3. Also, the reaction of compound 1 with benzaldehyde under a basic condition produced chalcone 4. Chalcone 4 can be used as a key intermediate for further preparation of heterocyclic compounds. In addition, compound 1 was allowed to react with malononitrile dimmer and/or ethyl chloroacetate to give pyrimidines 8 and 9, respectively.Alkylation of compound 8 with ethyl chloroacetate afforded S-alkylated product 10 which was treated with hydrazine hydrate to yield the hydrazino derivative 11. Alternative synthesis of compound 10 was taken place through reaction of compound 9 with malononitrile dimmer. The biological activity of the synthesized compounds was investigated. Compounds 1, 4, 5, and 8 recorded high activities against Gram positive bacteria (S. aureus). Structures of the new synthesized compounds were elucidated by elemental analysis and spectral data.