Development of a redox-free Mitsunobu reaction exploiting phosphine oxides as precursors to dioxyphosphoranes

The development of the first redox-free protocol for the Mitsunobu reaction is described. This has been achieved by exploiting triphenylphosphine oxide - the unwanted by-product in the conventional Mitsunobu reaction - as the precursor to the active P(V) coupling reagent. Multinuclear NMR studies are consistent with hydroxyl activation via an alkoxyphosphonium salt.