Arylidene-2-aminobenzimidazoles (1) were prepared by condensation of 2-aminobenzimidazole with aromatic aldehydes. Cyclocondensation of mercaptoacetic acid, chloracetylchloride and phthaloyl glycyl chloride on 1 giving the corresponding 4-thiazolidinones (2) and azetidinones (3 and 4) respectively, in good yields. The biological activities of the prepared compounds were screened against several strains of bacteria.

The reaction of N-(3-carbethoxy-4,5,6,7-tetrahydrobenzo[b]thien-2-yl)-N-phenylthiourea (1) with hydrazine hydrate in 1-butanol afforded a mixture of compounds 2, 3 and 4. Treatment of 3 and 4 with nitrous acid gave 6 and 8 respectively, while reactions of 3 with acetylacetone gave 7. Synthesis of tetracyclic compounds 9a-f and 11 from the reactions of 3 with ethyl orthoformate or appropriate acids, acid chloride, carbon disulphide and/or ethyl chloroformate. Also its reaction with isothiocyanate derivatives gave the corresponding thiosemicarbzides 12a,b which on, refluxing in alcoholic KOH gave the unexpected tetracyclic products 14a,b. Similarly the tetracyclic compounds 16a-e and 19 were obtained by cyclization of 4 and 18 respectively.

The reaction of N-(3-carbethoxy-4,5,6,7-tetrahydrobenzo[b]thien-2-yl)-N-phenylthiourea (1) with hydrazine hydrate in 1-butanol afforded a mixture of compounds 2, 3 and 4. Treatment of 3 and 4 with nitrous acid gave 6 and 8 respectively, while reactions of 3 with acetylacetone gave 7. Synthesis of tetracyclic compounds 9a-f and 11 from the reactions of 3 with ethyl orthoformate or appropriate acids, acid chloride, carbon disulphide and/or ethyl chloroformate. Also its reaction with isothiocyanate derivatives gave the corresponding thiosemicarbzides 12a,b which on, refluxing in alcoholic KOH gave the unexpected tetracyclic products 14a,b. Similarly the tetracyclic compounds 16a-e and 19 were obtained by cyclization of 4 and 18 respectively.

4-Methyl-6-mercapto-2-phenylpyrimidine-5-carbonitrile ( 1 ) was reacted with different halo compounds, namely ethylchloroacetate, chloroacetone, bromoacetanilide, p-chlorobromoacetanilide, and p -methoxy chloroacetanilide in ethanol in the presence of sodium acetate yielded the corresponding S-alkylated derivatives ( 2a-e ). The latter compounds underwent cyclization into thienopyrimidines ( 4a-e ) upon treatment with sodium ethoxide in ethanol. The reaction of ( 4a ) with hydrazine hydrate led to the formation of 5-amino-4-methyl-2-phenylthieno[2,3-d]pyrimidine-2-carbohydrazide ( 5 ). Compound ( 5 ) was reacted with a variety of reagents to produce other new thienopyrimidines as well as oxadiazolylthienopyrimidines ( 6, 11 ).