Ultrasound-assisted solvent-free synthesis of 3, 4-dihydropyrimidin-2(1H)-ones/thiones using polyindole as a recyclable catalyst

ABSTRACT

This paper describes the synthesis of polyindole by chemical oxidative polymerization using copper chloride as oxidant. Polyindole was characterized by various spectroscopic techniques like FT-IR, XRD, FESEM, and TGA. The XRD pattern confirms the semi-crystalline nature of polyindole. An efficient, solvent-free, ultrasound-assisted synthesis of biologically active 3,4-dihydropyrimidin-2(1 H)-one/thiones (DHPM) derivatives is reported by using polyindole as a recyclable catalyst. The advantages of this method are mild reaction conditions, short reaction time, excellent yields with high purity and low loading of catalyst. Polyindole can be used several times without loss of significant catalytic activity as compared to the other reported catalysts. Factors affecting on the rate of reaction, like use of ultrasonication, temperature, solvent, amount, and recyclability of catalyst have also been studied.

Graphical abstract

KEYWORDS:

• Polyindole
• ultrasonic irradiation
• 3
• 4-dihydropyrimidin-2(1H)-one/thiones
• solvent-free

Acknowledgments

The authors are grateful to the Board of College and University Development (BCUD), ISRO, Savitribai Phule Pune University, Department of Science Technology (DST) for providing financial assistance, C-MET and NCL, Pune for characterization. We also thank Nowrosjee Wadia College, Pune for providing lab facility.

Supplementary material

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Additional information

Notes on contributors

Kalpana N. Handore

Kalpana N. Handore is Assistant professor in organic chemistry  at Nowrosjee Wadia College,  Savitribai Phule Pune University, Pune Maharashtra. She has more than 15 years teaching experience for Under graduate and Post graduate courses. She has background in organic, polymer and medicinal chemistry, and expert in synthesis of hetrocyclic biological active molecules. She has 12 publications  international journals and contributed to 3 book chapters.

Vasant V. Chabukswar

Dr. Vasant V. Chabukswar is professor in Nowrosjee Wadia College, Savitribai phule university, Pune Maharashtra. He has more than 28 years of teaching organic chemistry for under graduate and post graduate courses. He has broad area of research  excellent in polymer chemistry, hetrocyclic organic synthesis, nanoparticle and medicinal chemistry. He has more than 44 international research articles and contributed to various book chapters.

Digamber Pawar

Digamber Pawar is the currently PhD fellow of Nowrosjee Wadia College, Savitribai phule Pune university, Pune. He has 15 years industrial experience and contributed to several patents. His research area includes synthesis of bioactive organic molecule and peptide synthesis. He has 1 publications in international journals including Medicinal chemistry.