Base induced rearrangement of N,O-bis(diphenylphosphinoyl)hydroxylamine: 18O-labelling evidence on how the phosphonamidic-phosphinic anhydride product is formed

Abstract

The ¹⁸ O-labelled substrate Ph ₂ P(O)NHOP( ¹⁸ O)Ph ₂ rearranges with base (KOBu ^t ) to give Ph(PhNH)P(O)OP( ¹⁸ O)Ph ₂ but not Ph(PhNH)P(O) ¹⁸ OP(O)Ph ₂ , in accord with a concerted mechanism rather than one involving a metaphosphonimidate intermediate; Ph(PhNH)P( ¹⁸ O)- OP(O)Ph ₂ is also formed, but only because the substrate rapidly equilibrates with Ph ₂ P( ¹⁸ O)NHOP(O)Ph ₂ prior to rearrangement.