Direct conversion of white phosphorus to versatile phosphorus transfer reagents via oxidative onioation

The main feedstock for the value-added phosphorus chemicals used in industry and research is white phosphorus (P-4), from which the key intermediate for forming P(III) compounds is PCl3. Owing to its high reactivity, syntheses based on PCl3 are often accompanied by product mixtures and laborious work-up procedures, so an alternative process to form a viable P(III) transfer reagent is desirable. Our concept of oxidative onioation, where white phosphorus is selectively converted into triflate salts of versatile P-1 transfer reagents such as [P(L-N)(3)][OTf](3) (L-N is a cationic, N-based substituent; that is, 4-dimethylaminopyridinio), provides a convenient alternative for the implementation of P-O, P-N and P-C bonds while circumventing the use of PCl3. We use p-block element compounds of type RnE (for example, Ph3As or Phi) to access weak adducts between nitrogen Lewis bases L-n and the corresponding dications [RnELN](2+). The proposed equilibrium between [RnELN](2+) + L-N and [RnELN)(2)](2+) allows for the complete oxidative onioation of all six P-P bonds in P-4 to yield highly reactive and versatile trications [P(L-N)(3)](3+).