Synthesis and Biological Evaluation of 7-N-(n-Alkoxyphthalimido)-2-hydroxy--4-aryl-6-aryliminothiazolidino[2,3-b]pyrimidines and RelatedCompounds. -With a view to their potential biological activity different kinds of compounds such as (V) and (VII) are prepared. The structure-activity relationships are discussed. (VIIb) shows high activity against Staphylococcus aureus. -(SINGH, B. S.; MEHTA, D.; BAREGAMA, L. K.; TALESARA*, G. L.; Indian J.

Thiazolidin-4-one fused pyrimidines, [1,5]-benzodiazepines and their oxygen substituted hydroxylamine derivatives have been screened for antibacterial, antifungal and antimalarial activity. Bacillus subtilis, Escherichia coli, Proteus mirabilis and Salmonella typhi were used for antibacterial screening. Aspergillus fumigatus and Candida albicans were used for antifungal screening and Plasmodium species were used for antimalarial screening. The antibacterial and antifungal activities are expressed in terms of zone of inhibition and antimalarial activity is expressed in IC50 value. Fifteen compounds 2Xa, 2Xb, 2Xc, 2Xs, 3IV, 3Va, 3Vc, 3VIIIa, 3VIIIh, 3IXa, 3IXb, 3IXc, 3Xa, 4IXa and 4Xa were tested for antibacterial as well as antifungal activity and seven compounds 2IXb, 2Xb, 3VIIIc, 3Xc, 4IXa, 4Xa and 4IXw were tested for antimalarial activity. Streptomycin, griseofulvin and chloroquine were taken as standard drugs in antibacterial, antifungal and antimalarial activity, respectively. The compound 2Xs was found significant antimicrobial against Bacillus subtilis, E. coli, Aspergillus fumigatus and Candida albicans as well as compound 3Xa was significant antimicrobial against Bacillus subtilis, E. coli, Salmonella typhi, Aspergillus fumigatus and Candida albicans. The compound 2Xb showed significant antimalarial activity.

A series of 2-N-ethoxyphthalimido 3-(4-substitutedphenyl)-6,6-diphenyl-3,3a-dihydro-2H-imidazo[2,1-b] pyrazolo[3,4-d][1,3]thiazol-7(6H)-one(7a-e) and 4-(4-substituted phenyl)-2-(N-ethoxyphthalimido amino)-7,7-diphenylimidazo[2 0 ,1 0 :2,3][1,3]thiazolo[4,5-d] pyrimidin-8(7H)-one (9a-e) have been designed and synthesized starting from thiohydentoin (1). The structure of all synthesized compounds has been established by IR, 1 H NMR, 13 C NMR and mass studies. These compounds have been screened for antimicrobial activities in order to evaluate the possibility of the derivatives to be used as potential chemotherapeutic agents.

8-Hydroxyquinoline 1 reacts with ethyl chloroacetate in the presence of anhydrous K 2 CO 3 to produce ethyl (quinolin-8-yloxy)acetate 2. Treatment of 2 with hydrazine hydrate forms 2-(quinolin-8-yloxy)acetohydrazide 3, which on condensation with various aldehydes 4a-e gives N'-{[(1Z)-arylmethylene]-2-(quinolin-8-yloxy)}acetohydrazides5a-e. These, on cyclization with mercaptosuccinic acid, yield (2-aryl-4-oxo-3-{[(quinolin-8-yloxy)acetyl]amino}-1,3-thiazolidin-5-yl) acetic acids 6a-e. Compounds 6a-e are further converted into acid chloride derivatives 7a-e by reaction with thionyl chloride. Subsequent treatment of 7a-e with N-hydroxysuccinimide in the presence of TEA furnishes the title compounds 8a-e. Antibacterial and antifungal activities of the final compounds have been evaluated and all the compounds have shown significant inhibition of bacterial and fungal growth.

A variety of phthalimido[2-aryl-3-(5′-(4′′-pyridyl)-1′,3′,4′-thiadiazol-2′-yl)-4-oxothiazolidin-5-yl]ethanoates 7a-h and 3-N-alkoxyphthalimido-2-isonicotinoylhydrazido-1,3-thiazolidin-4-ones 9a-c were synthesized using thiosemicarbazide of isoniazid 2 by two alternative pathways. The structures of these compounds were confirmed by IR, NMR ( 1 H & 13 C) and Mass spectral studies. Synthesized compounds 7a-h and 9a-c were evaluated for their antimicrobial activity. Some of the compounds exhibited good antimicrobial activity compared to standard drugs. The structure activity relationships of synthesized compounds have also been studied in order to develop the most potential antimicrobial agent for preclinical evaluation.