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 PCl 3 . Owing to its high reactivity, syntheses based on PCl 3 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 PCl 3 . We use p-block element compounds of type R n E (for example, Ph 3 As or PhI) to access weak adducts between nitrogen Lewis bases L N and the corresponding dications [R n EL N ] 2+ . The proposed equilibrium between [R n EL N ] 2+ + L N and [R n E(L N ) 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+ .