Catalyst-free UV₃₆₅-assisted synthesis of pyran annulated heterocyclic scaffolds and evaluation of their antibacterial activities

Abstract

A convenient and eco-friendly, one-pot synthetic protocol for pharmaceutically important pyran-based heterocyclic compounds is repeated herein. The reactions were carried out at room temperature in a water–ethanol solvent mixture under direct irradiation of UV₃₆₅ light source in the absence of photocatalyst. The merits of the present protocol include mild and catalyst-free reactions, green procedures, and high yields. The added advantage of this protocol is that it can be applied for large-scale synthesis of various pyran-based heterocyclic compounds without employing any expensive catalyst. Also, in vitro antibacterial screening of pyran derivative was investigated against both Gram-positive Bacillus cereus (B. cereus) and Gram-negative bacteria Escherichia coli (E. coli).

Graphical Abstract

Keywords:

• Antimicrobial activities
• catalyst-free
• Knoevenagel condensation
• pyran-based heterocycles
• UV-365 photo-irradiation

Acknowledgments

The authors would like to acknowledge Dr. M. K. Sahoo for allowing the use of the UV photoreactor. SAIF-NEHU, Department of Chemistry-NEHU, and CDRI Lucknow are highly acknowledged for providing various analytical assistance. The support from Prof. Dhruva Kumar Jha (Gauhati University) is gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors would like to thank DST for financial support (sanctioned no.: EEQ/2016/000646). DST-SERB.