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 (P4), 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 P1 transfer reagents such as [P(LN)3][OTf]3 (LN 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 LN and the corresponding dications [RnELN]2+. The proposed equilibrium between [RnELN]2+ + LN and [RnE(LN)2]2+ allows for the complete oxidative onioation of all six P-P bonds in P4 to yield highly reactive and versatile trications [P(LN)3]3+.