Hemi-synthesis of novel chiral benzodiazepine derivatives from Eucalyptus citriodora essential oil: 2D NMR experiments and differential scanning calorimetry study of diastereoisomers

Abstract

An efficient in situ condensation of citronellal, the main constituent of Eucalyptus citriodora essential oil (51%), with different amine derivatives of 2,3-diaminomaleonitrile and 3-[(2-aminoaryl)amino]dimedone has led to novel chiral benzodiazepine structures. All reactions were precipitated in ethanol and pure products were obtained in good yields (58–75%) without any purification. The synthesized benezodiazepines were characterized by spectroscopic techniques, namely ¹H-NMR, ¹³C-NMR, 2D NMR and FTIR. Differential Scanning Calorimetry (DSC) and HPLC were used to confirm the formation diastereomeric mixtures of benzodiazepine derivatives.

Graphical Abstract

Keywords:

• Hemi-synthesis
• Eucalyptus citriodora
• benzodiazepines
• essential oil
• differential scanning calorimetry

Acknowledgments

We gratefully thank the Algerian Ministry of Higher Education and Scientific Research and the Algerian General Directorate of Scientific Research and Technological Development for the availability and the open doors of their research institutions. We wish to thank Dr Bachari Khaldoun from the National Center of Scientific Research in Physico-Chemical Analysis (CRAPC).

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.