One-Pot Biginelli Synthesis of New Pyrazole–Tetrahydropyrimidinethione Hybrids as Promising Antimycobacterial Agents

Novel pyrazole–tetrahydropyrimidinethione hybrids were synthesized via a modified Biginelli reaction with a new 1,3-dicarbonyl compound derived from 1-methyl-1H-pyrazol-3-amine and ethyl aceto­acetate. 6-Methyl-N-(1-methyl-1H-pyrazol-3-yl)-4-(substituted phenyl)-2-sulfanylidene-1,2,3,4-tetrahydro­pyrimidine-5-carboxamide derivatives were obtained in high yields using concentrated HCl as a catalyst. The products were characterized by NMR (1H and 13C) spectroscopy and mass spectrometry and evaluated for their antitubercular activity against M. tuberculosis H37Rv. The 4-(trifluoromethyl)phenyl derivative showed the best activity (MIC = 3.12 μg/mL), while 4-fluorophenyl and 4-nitrophenyl analogues showed moderate efficacy (MIC = 6.25 and 12.5 μg/mL, respectively).