Synthesis of some biologically active agents derived from thieno[2,3-d]pyrimidine derivatives

The key compound 1-amino-8-iminocyclopenta[b]thieno[2,3-d]pyrimidine (5g) was prepared by reaction of 2-amino-3-cyano cyclopenta[b]thiophene (1) with triethyl orthoformate followed by cyclization with hydrazine hydrate in ethanol. Refluxing of 1 with triethyl orthoformate in the presence of acetic anhydride gave an unexpected product 2. while reaction with aromatic amines gave the condensation products 4a-c. Reaction of 5g with formic acid, other formate derivatives, ethoxymethylenemalononitrile and ethyl ethoxymethylenecyanoacetate gave the same product cyclopentathieno-[2,3-d]-1,2,4-triazolo[3,2-f]pyrimidine 6. Compound 7 was prepared by different methods. Treatment of 5g with dicarbonyl compounds gave the triazol derivatives 8-11. Reaction of 5g with phenyl isothiocyanate, carbon disulphide and ethyl chloroformate gave the corresponding derivatives 12-14, respectively. Condensation of 5g with some selected aromatic and heterocyclic aldehydes, acetone, N-acetyl isatin and isatin gave the condensation products 15a-e, 16-18, respectively in good yields. Many of the synthesized compounds were tested in vitro for their inhibitory activity against a variety of bacteria such as: Serratia rhodnii, Bacillus cereus, Staphylococcus citreus and Pseudomonas aeruginosa and fungi such as: Aspergillus flavus, Penicillium chrysogenum and Alternaria alternarta. Some compounds showed modest activity.