Concise and Facile Synthesis of Novel Pyrano[2,3-d]pyrimidine-7- one/thione Derivatives as In Vitro Antimicrobial and Antitubercular Agents

Inspired by the broad bio-activity of pyran and pyrimidine based heterocyclic compounds, novel 5-amino-4- (substituted phenyl)-3-methyl-1-phenyl-4,8-dihydropyrazolo[4' ,3' :5,6]pyrano[2,3-d]pyrimidine-7(1H)-one 2(a-j) and 5- amino-4-(substituted phenyl)-3-methyl-1-phenyl-4,8-dihydropyrazolo[4' ,3' :5,6]pyrano[2,3-d]pyrimidine-7(1H)-thione 3(a-j) have been synthesized from 6-amino-4-(substituted phenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3- c]pyrazole 1(a-j). All the newly synthesized compounds have been characterized by IR, 1H NMR, 13C NMR, Mass spectra and elemental analysis, and screened for antimicrobial and antitubercular activities. Among the synthesized compounds, 4-Cl (2g) derivative of fused pyrimidone analogues revealed good antimicrobial activity. Among the precursors, only the compound bearing 4-CH3 (1j) has been found to show 97% inhibition against Mycobacterium Tuberculosis H37Rv while the compounds 4-F (2d) and 3-NO2 (2h) in pyrimidone analogues and 4-OH (3c) and 4-Cl (3g) in pyrimidine thione analogues demonstrated remarkable antitubercular activity.