Sulfonylation in the rearrangement of an N-phosphinoyl-O-sulfonyl- hydroxylamine: demonstration of a phosphonamidic-sulfonic anhydride intermediate and 18O-labelling evidence on how it may be formed

Abstract

The rearrangement reaction of R(Ph)P(O)NHOSO ₂ Bn (R = PhMeCH) (57% enriched with one ¹⁸ O atom in the SO ₂ group) with Bu ^t NH ₂ in CH ₂ Cl ₂ gives the sulfonamide BnSO ₂ NHBu ^t (43.7% enriched with one ¹⁸ O atom) as one of the products; this indicates a phosphonamidic-sulfonic anhydride intermediate [R(BnSO ₂ O)P(O)NHPh], formed with partial equilibration of the sulfonate oxygen atoms and attacked (in part) at the sulfonyl group.