Synthesis of New Tetraethyl(N-alkyl-1-aminoethan-1,1-diyl)bisphosphona-tes and ESR Analysis of Chemical Exchange of Derived Nitroxides of Acyclic Aminobisphosphonates

Abstract

The synthesis and the full characterization of two new linear bisphosphonates (tetraethyl(N-tert-butyl-1-aminoethan-1,1-diyl)bisphosphonate and tetraethyl(N-sec-butyl-1-aminoethan-1,1-diyl)bisphosphonate), and the first analysis of the ESR spectra of the corresponding nitroxides is reported. The preliminary results of theoretical calculations on model compounds suggest a small B₀ (in the McConnell equation). The results of bisphosphonate ester and bisphosphonic acid are similar. The discrepancies of P coupling for the diphosphorus compound stems from B₂ that is different when the dihedral angle is larger than 90°.

Keywords:

• Bisphosphonates
• diphosphorylation
• ESR
• McConnell equation
• nitroxide
• theoretical calculations

Acknowledgments

We thank the Hungarian Scientific Research Fund OTKA T-046953 for the financial support. We also thank M. David Riffont from EICVN for his help.

This manuscript is dedicated to the memory of Jean-Pierre Finet.