S. D. Tala

Multi-component synthesis of dihydropyrimidines by iodine catalyst at ambient temperature and in-vitro antimycobacterial activity.

An efficient and simple three‐component domino synthesis of some new dihydropyrimidines (DHPMs) from aromatic aldehydes, 1,3‐dicarbonyl compounds and N‐(3‐chloro‐4‐fluorophenyl)urea using molecular iodine as catalyst is described. The 1‐substituted dihydropyrimidines were isolated in good to excellent yields (78‐90%) within a short reaction time (4‐6 h) at ambient temperature. The biological evaluation revealed that the newly synthesized compounds (4a‐i and 5a‐i) exhibited moderate antimycobacterial activity against Mycobacterium tuberculosis H37 RV.

Synthesis of Some New 1,2,3,4-Tetrahydropyrimidine-2- thiones and Their Thiazolo[3,2-a]pyrimidine Derivatives as Potential Biological Agents

Some new N-(4-chlorophenyl)-6-methyl-4-aryl-2-thioxo-1,2,3,4-tetrahydro pyrimidine-5-carboxamide 4(a–h) were synthesized by the reaction of N-(4-chlorophenyl)-3-oxobutanamide, thiourea and different aromatic aldehydes. The synthesis of N-(4-chlorophenyl)-7-methyl-5-aryl-2,3-dihydro-5H-thiazolol[3,2-a]pyrimidine-6-carboxamide 5(a–h) was accomplished by cyclocondensation of 1,2,3,4-tetrahydropyrimidine-2-thiones 4(a–h) and 1,2-dibromoethane. The structures of these compounds have been proved by IR, 1H-NMR, and Mass spectral studies. Synthesized compounds 4(a–h) and 5(a–h) were evaluated for their antimicrobial activities. Some of the compounds exhibited significant inhibition on bacterial and fungal growth as compared to standard drugs.

Synthesis of Some New Pyrazolo[3,4-d]pyrimidines and Thiazolo [4,5-d]pyrimidines and Evaluation of Their Antimicrobial Activities

The desired fused ring system 3-isopropyl-4-aryl-1,4,5,7-tetrahydro-pyrazolo[3,4-d]pyrimidine-6-thiones 4a–d were synthesized by the reaction of 5-isopropyl-2,4-dihydro-3-pyrazolone 1, thiourea and different aromatic aldehydes, while 7-aryl-5-thioxo-4,5,6,7-tetrahydro-3H-thiazolo[4,5-d]pyrimidin-2-ones 7a–d were synthesized by using 2,4-thiazolidine 5 instead of 5-isopropyl-2,4-dihydro-3-pyrazolone 1. The structure of the compounds was assigned on the basis of elemental analysis, IR, 1H-NMR, and mass spectroscopy. The antibacterial activity of the newly synthesized compounds were tested against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 1539, and their antifungal activity against Candida albicans ATCC 10231 were tested using the disk diffusion method. Compounds 4b, 4c, 4d, 7c and 7d were found to be active against S. aureus ATCC 6538 (MIC: 185; 78; 156; 78; and 102 μ g/Ml, respectively) and compounds 4d and 7d against C. albicans ATCC 10231 (MIC: 312.5 μ g/mL). The minimum inhibitory concentration of these compounds was determined using the micro dilution method.