Succinct and Facile Synthesis of Innovative Thiopyrimidines With Antimicrobial and Antitubercular Investigation

Abstract

To develop a series of bioactive heterocycles in minimum number of steps, 3-methyl- 4-(substituted phenyl)-1-phenyl-4,8-dihydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5,7 (1H,6H)-dithione 2(a–j), 4-(4-substituted phenyl)-5-imino-3-methyl-1,6-diphenyl-4,5,6,8-tetrahydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-7(1H)-thione 3(a–j), and N-[4-(subs- tituted phenyl)-3-methyl-1-phenyl-7-thioxo-1,4,7,8-hexahydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5-yl]thiourea 4(a–j) have been synthesized from amino nitrile functionality 1(a–j). The structures of the compounds were elucidated by IR, ¹H NMR, elemental analysis, and some representative ¹³C NMR and mass spectra. All the title compounds were screened for antimicrobial and antitubercular activities, while some representative compounds were tested for antioxidant activity. Out of synthesized compounds, compounds 1j (4-CH₃), 2d (4-F), 4c (4-OH), and 4i (3-Br) exhibited maximum inhibition against Mycobacterium Tuberculosis H₃₇Rv. Compound 3c (4-OH) revealed elevated efficacy against all tested bacterial strain, while compounds 1i (3-Br), 2c (4-OH), and 3h (3-NO₂) were found efficacious against Candida albicans as compared to standard drugs.

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GRAPHICAL ABSTRACT

Keywords:

• Thiopyrimidines
• pyrimidine dithione
• antimicrobial activity
• antitubercular activity
• antioxidant activity

Acknowledgments

The authors are thankful to the Department of Chemistry, V. N. S. G. University, Surat, for laboratory and some analytical facilities, and Atul Ltd, Valsad, for library and chemical facilities. The authors also thank Microcare Laboratory, Surat, for antimicrobial and antitubercular activities, and Biogenics, Research & Training Centre in Biotechnology, Karnataka, for antioxidant activity. The authors are grateful to RTML, Vapi, SAIF, Chandigarh and CDRI, Lucknow, for analytical facilities.