Synthesis and anti-bacterial activity of novel dihydrochromeno[8,7-e][1,3]oxazine-2(8H)-thiones

Abstract

A novel series of sulfur-containing dihydrochromeno[8,7-e][1,3]oxazine-2(8H)-thiones has been synthesized through an eco-friendly Mannich-type condensation cyclization reaction of 7-hydroxy-4-methyl-2-thiocoumarin or 6-chloro-7-hydroxy-4-methyl-2-thiocoumarin with formaldehyde and primary amines in water at 80–90°C for 2 h. All the synthesized compounds were screened for their in vitro anti-bacterial efficacy against two Gram-positive and three Gram-negative bacterial strains by using the disc diffusion method. The compound (8c) was found to be most potent with the zone of inhibition of 16 and 15 mm against Staphylococcus aureus ATCC 2937 and Klebsiella pneumoniae ATCC 31488, respectively.

GRAPHICAL ABSTRACT

Keywords:

• thiocoumarins
• dihydro[1,3]oxazines
• Lawesson's reagent
• Mannich reaction
• anti-bacterial activity

Acknowledgements

We thank the University of Delhi for financial support. B.P.M. is thankful to CSIR, New Delhi, India, for awarding the Senior Research Fellowship (SRF).