Unexpected formation of 4,5-dihydro-1H-pyrazolo[3,4-b]pyridine derivatives as a potent antitubercular agent and its evaluation by green chemistry metrics

Abstract

The present study describes L-hydroxy proline catalyzed unpredicted formation of 4,5-dihydro-1H-pyrazolo[3,4-b]pyridines instead of expected 4,7-dihydro-1H-pyrazolo[3,4-b]pyridines in aqueous ethanol at ambient temperature through one-pot three-component reaction. Furthermore, this protocol was evaluated using green chemistry metrics indicating green relevance of the present synthetic methodology. Most of the synthesized compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis H37RV strain, showing excellent results based on minimum inhibitory concentrations (MIC). Among the screened derivatives 4f, 4i, and 4j exhibited antitubercular activity with promising MIC value of 1.6 μg/mL.

Graphical Abstract

Keywords:

• Pyrazolo[3,4-b]pyridine
• green chemistry metrics
• antitubercular activity

Acknowledgments

Authors are thankful to Shivaji University, Kolhapur and Shri Shivaji Mahavidyalaya, Barshi, for providing laboratory facilities and liberal support. The authors also acknowledge to Instrumentation Department, Solapur University, Solapur for carrying out spectroscopic investigation and Maratha Mandal’s NGH Institute of Dental Sciences and Research Centre, Belgaum for anti-TB activity.

Additional information

Funding

We acknowledge the University Grant Commission, Western Regional Office, Pune [Grant Number-File No: 47-616/13(WRO)] for minor project.