L-proline catalyzed multicomponent domino reaction in polyethyleneglycol-400 for regioselective synthesis of pyrazolyl-tetrahydroindazolones under microwave irradiation

Abstract

A simple and convenient approach for the synthesis of pyrazolyl-tetrahydroindazolones via L-proline catalyzed three component domino reaction of arylhydrazine, dimedone and pyrazole aldehyde in polyethyleneglycol-400 (PEG-400) under microwave irradiation is described. This novel and green protocol proceeds smoothly in good to excellent yields and provides several advantages such as shorter reaction time, metal-free reaction conditions, simple work-up procedures. Also, recycling of the catalyst and solvent was observed without the loss of activity for three (03) runs.

Graphical Abstract

Keywords:

• Green synthesis
• L-proline
• Multicomponent domino reaction
• PEG-400
• Tetrahydroindazolone

Acknowledgments

The authors are grateful to SAIF and University Scientific Instrumentation Center (USIC), Karnatak University, Dharwad, India for providing the spectral and X-ray data and facilities to conduct the experiments. One of the authors PKB acknowledges Government of Karnataka, Bengaluru, for awarding Vidyasiri Fellowship.

Disclosure statement

The authors have declared no conflicts of interest.

Additional information

Funding

The authors are thankful to University Grant Commission, New Delhi, India for providing financial assistance under UGC-UPE thrust area “Antitumor activity: An integrated Approach” vide [F. No. 14-3/2012(NS/PE) Dated: 14-03-2012].