Exploring an Umpolung strategy for quaternization of phosphorus

Abstract

We propose a new, potentially widely-applicable, Umpolung approach for the synthesis of quaternary phosphonium salts R₃PR¹ X (X = Cl, Br) from phosphine oxides R₃PO. The new organic group R¹ is introduced via nucleophilic attack on an intermediate halophosphonium salt using a Grignard reagent R¹MgX and replaces the traditional phosphine quaternization approach. Consequently, the new method does not suffer from the limited availability of many parent phosphines and is much faster than standard quaternization.

GRAPHICAL ABSTRACT

Keywords:

• Nucleophilic substitution
• quaternary phosphonium salts
• Wittig reagents
• Umpolung

Additional information

Funding

This work was supported by Science Foundation Ireland through the SFI-funded Synthesis & Solid State Pharmaceutical Centre 12/RC/2275 Grant to D. G. G. We also thank Dr Kamalraj Rajendran for preliminary studies.