Direct Synthesis of Cyclic Phosphoramides From White Phosphorus Prompted by Dichalcogenides.

A chlorine-free approach was developed to synthesize cyclic phosphoramides from white phosphorus (P4). Using organic disulfides and diphenyl diselenide as both the mediators and reactants, white phosphorus could react with amino alcohols smoothly to generate cyclic phosphoramides in moderate-to-good yields (34%-95%). This one-step approach features mild reaction conditions and a simple operational process without chlorination. Mechanistic studies showed that the P═O double bond in the product was formed via possible bicyclic quaternary phosphonium salt intermediates. In addition, the organic disulfides/diselenides could be recycled without the addition of external oxidants.