An efficient synthesis of novel coumarinyldihydropyrimidin-2-thiones via coumarinylenones

Abstract

The novel coumarinyldihydropyrimidin-2-thiones (coumarinyl-DHPM) have been synthesized by Knoevenagel condensation of 4-formylcoumarins with different β-keto esters in the presence of aluminum chloride (AlCl₃) as Lewis acid catalyst leading to coumarinylenones followed by cyclization with protected thiourea and subsequent deprotection of protected sulfur intermediate by trifluoroacetic acid. The structures of coumarinylenones, protected intermediate and the desired coumarinyl-DHPM were confirmed by their NMR and X-ray diffraction analysis.

Graphical abstract

Keywords:

• 4-formylcoumarin
• Lewis acid catalyst
• coumarinyl-DHPM
• Knoevenagel condensation
• 2-thioxo-3,4-dihydropyrimidine

Acknowledgments

A.T. is thankful to the University of Delhi for providing financial support under DU-DST Purse Grant and R & D scheme. For the execution of the work, S.S. thanks UGC for providing Junior and Senior Research Fellowships. All the authors are also thankful to the Department of Chemistry and USIC, University of Delhi for providing the necessary facilities to conduct the experiments and instruments for characterization of compounds.

Author contributions

A.T. and S.S. designed, planned, conducted, and analyzed the experiments. K.M. conducted the X-ray diffraction experiments and solved the data for the crystal structures. S.S. and R.K directed the project and wrote the manuscript with contributions by A.T. and K.M. All the authors contributed to the discussions.

Conflicts of interest

All authors declare that they have no conflicts of interest.