CeCl₃·7H₂O Catalyzed, Microwave-Assisted High-Yield Synthesis of α-Aminophosphonates and their Biological Studies

Abstract

A new class of diethyl(3,5-dibromo-4-hydroxyphenylamino) (substituted phenyl/heterocyclic) methylphosphonates 4(a–j) has been synthesized by one-pot three component simultaneous reaction (Kabachnik–Fields) of 4-amino-2,6-dibromophenol 1, substituted heterocyclic/phenyl aldehydes 2(a–j), and diethylphosphite 3 using a Lewis acid catalyst, CeCl₃·7H₂O (5 mol%) under microwave irradiation as well as conventional conditions. It was observed that microwave irradiation method is more facile, efficient, and advantageous with respect to reaction time and yields. The structures of all the synthesized compounds were supported by analyzing IR, ¹H/¹³C/³¹P NMR, and mass spectral data. The synthesized compounds were screened for their in vitro antimicrobial and antioxidant activities.

GRAPHICAL ABSTRACT

Keywords:

• α-Aminophosphonates
• Lewis acid catalyst (CeCl₃·7H₂O)
• microwave irradiation
• antimicrobial and antioxidant activities

Acknowledgments

The authors are grateful to acknowledge financial support from University Grants Commission [UGC F.No. 40-71/2011(SR)] under which this research was carried out, one of the authors M. Varalakshmi wishes to thank University Grants Commission [RGNF, F1-17.1/2011-12] for providing the financial support through RGNF. The authors are also thankful to B. Vijaya Lakshmi, Osmania University, Hyderabad for providing the spectral data and would like to thank Jeanne Gilbert, USA and D. Subba Rao, S.V. University, India for providing technical support to the final manuscript.