4,5-Dihydro-1H-pyrazolo[3,4-d]pyrimidine containing phenothiazines as antitubercular agents

A series of novel dihydropyrazolo[3,4-d]pyrimidine derivatives bearing a phenothiazine nucleus were synthesized in excellent yields via a modified Biginelli multicomponent reaction. The newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, Mass spectra and elemental analysis followed by antimycobacterial screening. Among all the screened compounds, compound 4g showed most pronounced activity against Mycobacterium tuberculosis (Mtb) with minimum inhibitory concentration (MIC) of 0.02μg/mL, making it more potent than first line antitubercular drug isoniazid.